PDF Viewer is incompatible with Adobe Reader 11.0.7. Adobe made some changes in this version, which broke the use of the Active X control.
This problem is not specific to PDF Viewer. It also happens with other development environments such as Delphi, Visual Basic, Python, Xojo, MatLab etc.
You can find several discussions on the web regarding this problem:
The short term solution is to revert back to Adobe Reader 11.0.6.
It can be downloaded here:
We hope Adobe will fix the issue soon. The official response they gave so far regarding 64-bit support, doesn’t make much sense since the issue can be reproduced on Windows 7 32-bit.
Update 30 September 2014
The issue has been solved with Adobe Reader version 11.0.9.