You have not entered your Provincial Parental Insurance Plan premiums paid from Box 55 of your T4 slip, or the amount entered is greater than the amount entered in Box I of your Relevé 1 slip.

I have the same problem except my box 55 is zero and my box I is also zero.

any ideas?

Your Box 56 in T4 should match Box I from RL1 and Box 55 in T4 is the same as Box H in RL1. Even if it shows zeros in your T4 just add them manually. Your Box 56 and I cannot be a zero value, match your Box 14. 

I hope this was helpful