Are you trying to create a full screen UI (like the welcome and finish pages?) If so then you need to put Call muiPageLoadFullWindow before your code and Call muiPageUnloadFullWindow after. If you aren't using any welcome or finish pages, you also need !insertmacro MUI_PAGE_FUNCTION_FULLWINDOW. It sounds like you have one of the MUI header text controls over your link. The link will be rendered on top but will not receive any mouse events.
Stu
Thanks for your help Stu, Spy++ was a great idea. After running it I was able to see that other transparent controls were over my links and that is why they were not working. I suppose the reason that they worked on 1018 dialogs is because I had to rearrange them in order to see them since they are lower down on the 1044 dialog. When I moved the links up in the Y direction to test they were no longer buried under the offending transparent controls.
The solution for me was to rearrange the order that I create controls so that the links are created first and the other controls created later. This caused the expected behavior.
Again, thanks for the help.