Can't upgrade from Adobe Acrobat Pro X installed with CS5.5 to Adobe Acrobat 2015

[drealeed]

I wanted to upgrade Adobe Acrobat Pro X, so I clicked on the "upgrade now" link on the welcome page. It took me to adobe.com, where I purchased the upgrade to Adobe Acrobat 2015.

When I tried to install it, the installer prompted me for the previous serial number and product. Adobe CS 6 for mac was listed in the product dropdown to enter a serial number but not Adobe CS 5.5. So this upgraded version won't install.

Why not? The version of Adobe Acrobat Pro X that came with CS5.5 is the same as the version that came with CS6. It makes no sense that I can upgrade from the latter but not the former.

[kglad]

contact adobe support during pst business hours by clicking here and, when available, click 'still need help', https://helpx.adobe.com/contact.html

[drealeed]

Support said that, although the version of Adobe Acrobat Pro X is identical in both the CS5.5 and the CS6 packages, I can upgrade from CS6 but not CS5. Since I had CS5.5 I need to but the full Adobe Acrobat 2016 version

Which is a load of horse-puckey in my opinion.  I'll be finding some other pdf generation to use and warning my friends away from Adobe Acrobat in the future, your upgrading process is a joke.