PDF not opening in Adobe Reader using openWithDefaultApplication

Hello all,

I'm having a huge problem.

I've developed an application that opens pdf files from the desktop using openWithDefaultApplication().

It works great on my development PC which has Acrobat Pro.

The files open in Acrobat Pro flawlessly.

It DOES NOT work on other PCs that only have Adobe Reader.

Someone please help!!

Does anyone know why my application won't open pdf files using Adobe Reader?

All tested PCs are running Windows 7 and Air 4.0.

I've tried with both Adobe Reader X and XI.

Thank you in advance,

Mr12.