I'm trying to use the in silico pcr tool.  I have primers that match my sequence, with restriction site added to the 5p end.

If I do in silico pcr with only the 3' part of the primer that matches the target sequence, I get a product.

If I add the restriction site to my primer, and set 'mismatches' equal to the number of added bases, I get no product. 

Seems like this should work.  Am I doing something wrong?