Chrome, Firefox, Safari have their own built in PDF viewer (IE does not). That maybe why it's not working.
The problem is that third party PDF
viewers doesn't support all form's features. The PDF needs to be downloaded
locally and filled out with either.
Also if your behind a firewall and you aren't allowed to except a unknown file you may have a problem.
1. Download Adobe Reader it's Free and available for most OS (PC, Apple, Droid, I Pad) http://get.adobe.com/reader/
2. ***Try "Save As" file to computer and then right click on file where you save it at and open it in Adobe Reader.***
3. In firewall situation you may be ask to Ok that you trust this file/ link if you select "Yes" a pop up box will show it's uploading and a "Thank You for submitting" will show up it should go though and if "No" you will need to save a copy and email it in.
4. Try Different computer
I hope this helps.