I don't understand the difference between filling in Section 1 Part A on one return and the same numbers on Section 1 Part B on the spouse's return, except that they give me two different answers!

We have one spouse who contributes to her own RRSP and withdrew $17,000 for the HBP. Her husband, who contributes to his own RRSP, withdrew $6,900 from his RRSP for the same HBP.

If I fill in his numbers in Part A of his return, I get a positive result on line 3, but if I fill in his numbers in Part B of her return, I get a zero sum. To me, the questions are the same, so why the different results. 

Am I supposed to fill in her numbers in Part A of her return and his numbers in Part B of her return and then his numbers in Part A of his return and her numbers in Part B of his return? 

It's very confusingly worded.