Citrix XenApp 6.5
When a User is logged to a citrix session, his local printers are mapped into the Citrix session. The user can print to printers that are installed as iPrint workstation-defined printer but not to printers that are installed as iPrint user-defined printer.
Please contact citrix for the latest client fix.
If you have installed a iPrint-printer as an user-defined printer, iPrint will create this in the registry under HKEY_CURRENT_USER. The Citrix Universal Proxy Driver is not reading HKEY_CURRENT_USER. This is causing the above mentioned problem. The latest Citrix client is able to read the HKEY_CURRENT_USER.