A suggestion and a hint:

You're always going to be emitting   Content-type: text/html so do so at the top of the script. Scattering "have I done this yet" logic throughout the script makes for a needless mess. A good place is right after you unbuffer stdout by doing   $|++; Now, when you've got a failure in one particular case, comment the bulk of that case out, substituting   print "Test\n"; or whatever. Then gradually comment less and less of the code for that case out until you find out what's causing the breakage.

This is a variant of another standard piece of debugging advice: Find the smallest fragment of code that demonstrates the problem. Often this exercise is sufficient to help you locate the problem. Doing this is a good habit to adopt.