>SELECT TABLE_A >SCAN FOR Amount<>0 > STORE Number TO xNbr > SELECT TABLE_B > LOCATE FOR Field1B=xNbr > * To be safe you should check here if the record is found or not > REPLACE Field2B WITH TABLE_A.Amount >ENDSCAN >Instead of selecting, why not just:
IF !EOF("Table_B") REPLACE Field2B WITH TABLE_A.Amount IN Table_B ENDIF