Foreign tax credit is less than claimed?

Hi.

I received a NR4 from Canada (code 40) [pension benefits - lump-sum payment]. How do I report this? I have also paid taxes on that lump-sum payment in Canada. I have completed a F1116 but the credit "approved" by TT is approximately only 70% of the taxes paid. Why? Will the difference (30%) carry over for the next year?  Which line on the F1040 should I see the the gross income received from the code 40?

 

Thanks to take all these questions, one by one.