USE ftab                   &&added by me
*	SELECT ftab 
	
	USE addition              in 0 && otherwise it would close the previously opened table
**	SELECT addition             
	if SEEK(addition.name,  'fTab', 'Name')  &&check for name 1st
	THISFORM.UpdateResultsWindow('error name already entered')
	ELSE
	THISFORM.continue()
	ENDIF

>IT points at the Seek line

SEEK works with the INDEX set. You may want to use SEEK() as a function instead and pass the tag order as the last (3rd) parameter.

See changes I made in the code.