Hello @SadokHanini 

To load the drop-down values dynamically, then we need to use fieldselecting event to load the values dynamically. Please find the example below. 

        protected virtual void SOOrder_UsrKNOrderReturnCodes_FieldSelecting(PXCache cache, PXFieldSelectingEventArgs e)
        {
            SOOrder row = e.Row as SOOrder;
            if (row != null)
            {
                List<string> allowedValues = new List<string>();

                foreach (KNAMICodes objAMICodes in PXSelect<KNAMICodes, Where<KNAMICodes.codeType, Equal<AMIConstants.ReturnCodes>,
                    And<KNAMICodes.isActive, Equal<True>>>>.Select(Base))
                {
                    allowedValues.Add(objAMICodes.Codecd);
                }
                e.ReturnState = PXStringState.CreateInstance(e.ReturnState, 10, true, typeof(KNAMICodes.codecd).Name, false, -1, string.Empty, allowedValues.ToArray(), allowedValues.ToArray(), false, null);
                ((PXStringState)e.ReturnState).MultiSelect = false;
            }
        }

I hope this will help you!!
 

Sadok,

This link also, you can review and verify once.

https://acumatica.programmingpedia.net/en/tutorial/9392/modifying-items-in-a-dropdown-list

@Naveen B  This site is not responding

Hi @Deetz URL might be changed, you can the below URL.

https://sodocumentation.net/acumatica/topic/9392/modifying-items-in-a-dropdown-list

@Naveen Boga 

Since you are using allowedValues.ToArray() twice, does that mean that you are setting the value of the selected item in the DDL to the display value for each item?