Filter Sales Orders using USER Defined Rest APi

Hey All 

I’m Trying to filter all sales orders using USER-DEFIND field 

 

I’m using this Endpoint 

Method : POST 

URI: https://exemple.acumatica.com/entity/default/22.200.001/SalesOrder?$custom=Document.AttributeCPQORDNBR.value
&$filter=custom.document.AttributeCPQORDNBR eq '00000110'&$top=100


but it not working even i can see the custom field in the JSON 

Error :

message\":\"An error has occurred.\",\"exceptionMessage\":\"The child type 'custom.document.AttributeCPQORDNBR' in a cast was not an entity type. Casts can only be performed on entity types.
 

Much appreciated 

Thanks