Certificate with thumbprint {} associated with HTTPS input endpoint HttpsIn does not contain private key.

When I deployed a Cloud service package (.cspkg and .cscfg files) to the Cloud service (classic) on Azure, it failed. Received the following error message in the Operation log (classic) UpgradeDeploymentBySlot (Faild):    "operationStatus": {

        "id": "f91291f9-73f8-ab14-91b3-c6ba418d5152",

        "status": "Failed",

        "httpStatusCode": 400,

        "error": {

            "code": "BadRequest",

            "message": "Certificate with thumbprint 5AA4.....68EA associated with HTTPS input endpoint HttpsIn does not contain private key."

        }

I already installed the SSL wildcard_xyz_com.pfx into the Cloud service (classic). It is shown under the Settings->Certificates.

I also installed the SSL wildcard_xyz_com.pfx into the PC that I use to compile and package the Cloud service project to get the package (.cspkg and .cscfg) files. I believe the SSL wildcard_xyz_com.pfx contain private key.

So, my question is which Certificate and in where is referring in this error message?

Thanks in advance for your help!