Clients have problem to connec the server

I am having problem with my clients connect to the RMS server.

I found the below event in my RMS event log.

A client request contains secure data that is not trusted and that cannot be 
processed. The following information was reported: 
Microsoft.DigitalRightsManagement.Licensing.UntrustedPersonaCertException: 
The account certificate supplied by the requestor was not issued by a 
trusted user domain server.
   at 
Microsoft.DigitalRightsManagement.Core.ComponentBase.ValidatePersonaCert(Persona
Certificate 
oPersonaCert)
   at 
Microsoft.DigitalRightsManagement.Licensing.PublishPipeline.GetClientLicensorCer
t(String[] 
PersonaCerts, IDrmsPropertyBag propertyBag)
   at 
Microsoft.DigitalRightsManagement.Licensing.PublishPipeline.GetClientLicensorCer
t(GetClientLicensorCertParams[] 
RequestParams, HttpRequest request, IIdentity userIdentity)

For more information, see Help and Support Center at

Does anyone here know what is the problem? My server uses HTTPS. If I 
configure my RMS server use HTTP, it works, but not for HTTPS.