There is no error with Federal, only error with Quebec: Negative proceeds of disposition has been specified for a T5008 capital transaction.
but I checked website from Revenue Quebec: https://www.revenuquebec.ca/documents/en/formulaires/rl/RL-18.G-V%282021-10%29.pdf
see P18, 3.14 for Box 21: A negative amount can be entered in box 21 only if the code FUT (“opération à termes”) or OPC (“contrat d’option”) is entered in box 15.
please help