Well, I've got a few problems right off the bat...
1. You have renamed milonic_src.js. There is no reason to do that, and, I think, programatically it can cause problems. Also, the JS call to that file is incorrect.
2. You have removed the copyright notices from all 3 code files. Not only does this not allow us to see what version of the code you are running or your license number, it is also illegal. A snip from the items you removed...
All Copyright statements must always remain in place in all files at all times
******* PLEASE NOTE: THIS IS NOT FREE SOFTWARE, IT MUST BE LICENSED FOR ALL USE *******
Please replace these notices in their entirety.
3. Your browser detection routine does not allow for Mac browsers (at least not Safari). I was redirected to a page telling me my cookies are disabled (they are not), and talking about how to fix this in IE. So, you are effectively preventing Mac users from purchasing your product(s).
Because of this redirect, and probably not being on IE, I am unable to see your problem. However, typically this is caused when a secure page is calling items (graphics, includes, etc.) from an http site, rather than https.
#2 above (at least) must be corrected for any further assistance.
Thank you.