Amount on Schedule 1 line 308 doesn't show the total amount from box 16 from all T4 slips

The total amount shown in box 16 from all T4 slips comes from the sum of the amount from line 308 on Schedule 1 plus line 448 from the T1 (amount flows from the T2204 if CPP overpayment is applicable).

Calculation:  Line 308 (S1) + line 448 (T1) = box 16 (T4)