sharepoint - Nintex Forms 2010 External Data Column Validation rule -

i'm trying achieve required validation on nintex form 2010 external data column connected external content type. using regular validation rule below check if empty.

1. externaldatacolumn == ""  2. isnullorempty({self}) 

however, after provide value field required validation still shows not satisfied type of field , same works other field types. tried implement custom javascript in "control settings" but, unfortunately, form settings not getting saved.

thanks in advance.

if go column settings, can set required field , nintex validation automatically. don't need worry it.