When installing the XenDesktop Feature Pack 1 VDA software on a clean virtual machine that has had no previous Virtual Desktop Agent (VDA) software installed; no option for configuring the VDA software appears during installation, such as controller location and the TCP/IP port. Furthermore, the software appears as ‘Citrix Virtual Desktop Core Services’ under Programs and Features (Add/Remove Programs) and no option is given to reconfigure the software:
This happens when the VDA software is installed using the ‘Virtual Desktop Agent Update’ software package, available under Downloads.
XenDesktop > XenDesktop 5.6 Feature Pack 1 (your edition).> Custom Downloads and select Virtual Desktop Agent Update:
Note: This software is an update to any existing VDA software, 5.0 or above, and is not meant to be installed as a standalone software.
This software installation package is named XdsAgent_x86.MSI (for 32-bit systems) or XdsAgent_x64.MSI (for 64-bit systems):
Install any previous 5.5 or 5.6 version of the VDA software first before installing the 5.6 Feature Pack 1 update. If you do not have a previous version available, download the entire ‘Delivery Controller and Additional Components’ package, listed as the first option under Custom Downloads, mount the enclosed XenDesktop56.ISO, and run AutoSelect.exe to install the VDA software.
After that installation, install the update. Both the Citrix Virtual Desktop Agent and the Citrix Virtual Desktop Core Services appear in Programs and Features (Add/Remove Programs). The Virtual Desktop Agent appears with a Change option, as displayed in the following screen shot:
…and Virtual Desktop Agent Core Services appears as version 126.96.36.199141:
Read the original article here on the Citrix knowledgebase.