Box 21, Total Capital Gains is your total capital gain from a trust. Box 21, Foreign Capital Gains shows that all or part of the amount in Box 21, Total Capital Gains is non-business income for foreign tax credit purposes. So you can’t have the Total Capital Gains as being less than Foreign Capital Gains. Foreign Capital Gains has to be equal or less.
If your actual slip is showing a value Foreign Capital Gains that is higher than what is in Total Capital Gains, then you may want to contact the organization that issued the slip for a corrected slip.