Type Name does not Exist Error

I’m trying to enable a field for edits during any document state.

• I created the field.
• I made it into a ComboBox
• I added it to a screen
• I enabled it via the workflows to be editable
• I cannot get the cache to unlock though

Attached is my error:
 

But that field exists and does have that name:

 

Did I mistype the cache segment? 

I selected the field, I chose EVENTS, I chose ROW SELECTED, I chose ADD HANDLER, KEEP BASE METHOD.

I then inserted two lines into that generated code brick:

      if (row == null) return;

      PXUIFieldAttribute.SetEnabled<ARInvoiceExt.usrIsRebate>(cache, row, true);

Can someone save me here?