Hi,
I modified the AR Invoice form added the SalesCatID for the Line tab. I’ve setup the binding and it displays the right information. I’ve enabled the field and set tab index, but when I click on the field, it greys out preventing me from changing the value.
Can you provide more details?
table.field , which sheet, types of controls, etc…
e.g. InvcDtl.SalesCatID - located on Erp.UI.App.ARInvoiceEntry.LineDetailPanel?
A really simple test with textboxes worked OK for me.

Hard for me to tell what is going on from your initial description.
Exactly what you did. InvcDtl.SalesCatID located on the Line/Detail tab. I used a combo box though. I can try with a textbox and see if that works instead.
Ref screenshot of combo that worked on a quick test here
Maybe you just need to tweak a setting(s)?
EpiDataSetMode - have you already tried RowsDataSet?
