grandma jo of 6

Hi all! I have been enjoying reading through some of the posts on here and see how everyone responds with suggestions and helpful tips. I'm hoping someone can lead me in the right direction with this pattern. I'm working on the Nine Patch Heart Block from McCalls Jan./Feb. 2013 issue.

I've cut the pieces correctly, checked and rechecked. When I sewed the first rectangle to the nine patch all went well. I sewed the white block to the other rectangle as directed. Then when I tried to sew this piece to the other side of the nine patch, it is too big! What the heck is happening??

Hopefully someone can help me figure this out.

Thanks

Joann