This error can occur if an incorrect Communication Security passphrase was provided during the initial configuration of the Performance Center Server, or if the passphrase on the ALM Platform was changed.
To solve the mismatch, update the Communication Security passphrase on the ALM Platform and on the Performance Center Server.
To reset the Communication Security passphrase on the ALM Platform:
1 Log in to Site Administration.
2 In the Site Configuration tab, update the contents of the COMMUNICATION_SECURITY_PASSPHRASE parameter.
3 Restart the HP Application Lifecycle Management service on the ALM Platform server.
To set the same Communication Security passphrase on the Performance Center Server:
1. On the machine where the Performance Center Server is installed, run the Performance Center Server Configuration Wizard:
* Start > Program Files > HP Performance Center Server > Tools > HP Performance Center Server Configuration Wizard
1. On the Communication Security page, enter the new Communication Security passphrase.
2. Click Next on all of the subsequent wizard pages and Finish to close the wizard.
After completing the above steps, retry adding the Performance Center server to Lab Management.
I hope this helps