@stephenward03 

I think your mobile code is not correct. it should follow this syntax

update screen "ERP_ScreenID" {
 update container "WSDL_ContainerName" {
 add field "WSDL_FieldName"
 }
}

means for your case it should be like

update screen IN202520 {
 update container "Item" {
 add field "Abv"
 .
 .
 }
}

I suggest taking T4xx courses on openuni site to familiarize yourself with the mobile development.

Development (acumatica.com)

@RohitRattan88 Thanks for the advice but the code you have suggested doesn’t work. I explained that when I remove my abv line then other 2 fields still appear, using the syntax Item#PurchaseUnit and Item#SalesUnit, so I think the syntax is correct.

The screen doesn’t have a container called ‘Item’ so I cannot add to that. It has 2 containers, ‘HeaderView’ and ‘ItemInventorySummary’. The full mobile code is below. My Abv line in written in the same style of the existing lines.

add screen IN202520 {
  openAs = Form
  add container "HeaderView" {
    add layout "HeaderLayout" {
      displayName = "HeaderLayout"
      layout = "HeaderSticky"
      add field "InventoryID"
    }
    add layout "FooterLayout" {
      displayName = "FooterLayout"
      layout = "FooterSticky"
      add layout "Line1" {
        displayName = "Line1"
        layout = "Inline"
        add recordActionLink "ReviewAvailability"
        add recordActionLink "ScanBarcode"
      }
      add group "ChangeModeGroup" {
        displayName = "Change Mode"
        collapsable = True
        collapsed = True
        add layout "Line3" {
          displayName = "Line3"
          layout = "Inline"
          add recordActionLink "ScanModePick"
          add recordActionLink "ScanModePack"
          add recordActionLink "ScanModeShip"
        }
        add layout "Line4" {
          displayName = "Line4"
          layout = "Inline"
          add recordActionLink "ScanModeReceive"
          add recordActionLink "ScanModePutAway"
        }
        add layout "Line5" {
          displayName = "Line5"
          layout = "Inline"
          add recordActionLink "ScanModeIssue"
          add recordActionLink "ScanModeInReceive"
          add recordActionLink "ScanModeInTransfer"
        }
        add layout "Line6" {
          displayName = "Line6"
          layout = "Inline"
          add recordActionLink "ScanModePhysicalCount"
          add recordActionLink "ScanModeItemLookup"
          add recordActionLink "ScanModeStoragePlaceLookup"
        }
      }
    }
    add field "Mode#Message" {
      displayName = " "
      textType = PlainMultiLine
    }
    add field "Mode#Instructions" {
      displayName = " "
      textType = PlainMultiLine
    }
    add field "Scan" {
      special = BarCodeScan
    }
    add field "Mode#MessageSound" {
      special = SoundAlert
    }
    add field "Description"
    add field "Item#ItemClass" {
      forceIsDisabled = True
    }
    add field "Item#Type" {
      forceIsDisabled = True
    }
    add field "Item#ProductWorkgroup" {
      forceIsDisabled = True
    }
    add field "Item#ProductManager" {
      forceIsDisabled = True
    }
    add field "Item#IsAKit" {
      forceIsDisabled = True
    }
    add field "Item#ValuationMethod" {
      forceIsDisabled = True
    }
    add field "Item#BaseUnit" {
      forceIsDisabled = True
    }
    add field "Item#Abv" {
      forceIsDisabled = True
    }
    add field "Item#PurchaseUnit" {
      forceIsDisabled = True
    }
    add field "Item#SalesUnit" {
      forceIsDisabled = True
    }
    add recordAction "Save" {
      behavior = Save
    }
    add recordAction "Cancel" {
      behavior = Cancel
    }
    add recordAction "ScanBarcode" {
      displayName = "Scan"
      behavior = BarCodeCameraScan
    }
    add recordAction "ScanModePick" {
      redirect = True
    }
    add recordAction "ScanModePack" {
      redirect = True
    }
    add recordAction "ScanModeShip" {
      redirect = True
    }
    add recordAction "ScanModeOutbound" {
      redirect = True
    }
    add recordAction "ScanModeReceive" {
      redirect = True
    }
    add recordAction "ScanModePutAway" {
      redirect = True
    }
    add recordAction "ScanModeItemLookup" {
      redirect = True
    }
    add recordAction "ScanModeStoragePlaceLookup" {
      redirect = True
    }
    add recordAction "ScanModeIssue" {
      redirect = True
    }
    add recordAction "ScanModeInReceive" {
      redirect = True
    }
    add recordAction "ScanModeInTransfer" {
      redirect = True
    }
    add recordAction "ScanModePhysicalCount" {
      redirect = True
    }
    add recordAction "ReviewAvailability" {
      displayName = "Review"
      behavior = Void
      redirect = True
      redirectToContainer = "ItemInventorySummary$List"
    }
    attachments {
      add type "jpg" {
        extension = "jpg"
      }
      add type "png" {
        extension = "png"
      }
      add type "pdf" {
        extension = "pdf"
      }
    }
  }
  add container "ItemInventorySummary" {
    displayName = "Inventory Summary"
    visible = False
    add field "Location" {
      forceIsDisabled = True
    }
    add field "Available" {
      forceIsDisabled = True
      listDisplayFormat = CaptionValue
    }
    add field "AvailableForShipment" {
      forceIsDisabled = True
      listDisplayFormat = CaptionValue
    }
    add field "Expired" {
      forceIsDisabled = True
      listDisplayFormat = CaptionValue
    }
    add field "OnHand" {
      forceIsDisabled = True
      listDisplayFormat = CaptionValue
    }
    add field "LotSerialNumber" {
      forceIsDisabled = True
      listDisplayFormat = CaptionValue
    }
    add field "ExpirationDate" {
      forceIsDisabled = True
      listDisplayFormat = CaptionValue
    }
    add field "BaseUnit" {
      forceIsDisabled = True
      listDisplayFormat = CaptionValue
    }
    attachments {
    }
  }
}

@stephenward03 

Please review following post:

How to add customized field for mobile application | Community (acumatica.com)

Hi @RohitRattan88, I’ve reviewed the post, but this isn’t the same problem I’m trying to resolve. I have been able to add a field to a screen, the sales and purchase unit field are working fine. The Abv field causes the problem. 

Sales and Purchase unit fields seem to be system fields however Abv seems to be custom field(if so, please make sure all custom fields start with Usr prefix).

link shows how to add custom fields to the mobile screen.