That is correct box 21 (gain or loss) is not populating 68140 of T936 if you have a capital loss on line 19900 of T3 but CRA is asking for 68140 to be populated. The amount on T3 has already incorporated the amount from Box 21 so not required again but CRA is incorrect in asking for it populated if the over amount on 19900 of T3 is negative.
Still cannot NETFILE.
