This page offers help on on understanding what's going on if it does not work. Probably the first place you should look is the FAQ, you're likely not to be the first one with a specific problem.
Understanding what's on the HDMI wire
If the software runs but there is no picture, and you've made sure that it's not something in the FAQ, it's time to start to debug your HDMI connection. HDMI debugging will always come down to plugging something in place of, or inline with, your capture card so you can see what's on the wire.