Question for the use of the AMTAlarmClock Feature with Powershell

Hit everyone.

AMTAlarmClock Feature via Powershell. When i try to use the code with a AMT 5.2.7.0 machine it Fails. A 8.0 Version works great.

The PDF documentation Shows that it should support machines over 5.1.

Is there something else i have to do with  the 5.2.7.0 machines?

Atm i use the following code

Set-AMTAlarmClock-ComputerName$Compi-Credential$a-TLS-AlarmTime:2014-09-10T11:00:00

The credentials are stored in a variable.

Thank's for the help.