volumefreespace isssue on remote servers


I am using policies in combination with EPM framework (see codeplex) to execute policies remotely. For some reason I cannot exec the volumefreespace facet on remote servers. The powershell script which fires the policies is executed in a job and I am using admin credentials/proxies to run this jobstep. The CMS server is 2008R2 and I got errors on both 2008 en 2012 servers (all remote). It must be a security issue, but I can't figure out what I forgot. Any ideas?

This is the error:
Microsoft.SqlServer.Management.Dmf.PolicyEvaluationException: Exception encountered while executing policy Datafiles kunnen niet groeien.  
---> Microsoft.SqlServer.Management.Dmf.MissingPropertyException: Property VolumeFreeSpace does not exist.    at Microsoft.SqlServer.Management.Dmf.Condition.Evaluate(Object target, AdHocPolicyEvaluationMode evaluationMode)
at Microsoft.SqlServer.Management.Dmf.ObjectSet.CalculateTargets(IEnumerable objectSet, Condition condition, AdHocPolicyEvaluationMode evaluationMode, Object[]& conforming, TargetEvaluation[]& violating)
at Microsoft.SqlServer.Management.Dmf.ObjectSet.CalculateTargets(SqlStoreConnection targetConnection, Condition condition, AdHocPolicyEvaluationMode evaluationMode, String policyCategory, Object[]& conforming, TargetEvaluation[]& violating)
at Microsoft.SqlServer.Management.Dmf.Policy.EvaluatePolicyUsingConnections(AdHocPolicyEvaluationMode evaluationMode, SfcQueryExpression targetQueryExpression, Int64& historyId, ISfcConnection[] targetConnections)  
--- End of inner exception stack trace ---