Ran into a generic issue while working with a customer recently.  The issue was that whenever they launched an application from within the network using the PNAgent or Citrix Online Plugin Full version as they call it now, they would get an error that Citrix was "Unable to launch your application. Contact your help desk with the following information.".

This error can be very generic and can point to many things.

First step if there is a CSG server that resides in the DMZ in place and communicates to the inside network Web Interface/Citrix Server is to install the agent on the CSG server in the DMZ and test.  If it works there you can be sure that all the necessary ports for XML and Session reliability are open and good to go.

In this instance it turned out that the automatic use of Internet Explorer's proxy settings was the issue.  We needed to bypass the proxy for the server in the DMZ from inside the network but needed to leave the settings in Internet Explorer.

The answer is a simple registry change that allows you to change the default proxy behavior of the Citrix Online Plugin.

Find the key(s)

HKEY_LOCAL_MACHINESOFTWARECitrixICA ClientEngineLockdown ProfilesAll RegionsLockdownNetworkProxy   

HKEY_CURRENT_USERSoftwareCitrixICA ClientEngineLockdown ProfilesAll RegionsLockdownNetworkProxy  

Update the value of the ProxyType from "Auto" or BLANK to the word "None".  This will bypass the proxy for the Citrix Client only.

Good Luck!
 