SSL OWA Cert Issue

[FASSET]

I am trying to install an SSL Certificate for OWA on our exchange server but keep hitting a brick wall (and no it`s not the firewall!!) whenever i try and submit a certificate, i receive the error below: i have tried all suggestions from other sites and even on here, i was wondering if anyone had a workaround.

Your request failed. An error occurred while the server was processing
your request.
Contact your administrator for further assistance.
Request Mode:

newreq - New Request
Disposition:
(never set)
Disposition message:
(none)
Result:
Access is denied. 0x80070005 (WIN32: 5)
COM Error Info:
CCertRequest:ubmit Access is denied. 0x80070005 (WIN32: 5)
LastStatus:
Access is denied. 0x80070005 (WIN32: 5)

[EINSTEIN_007]

Did you follow the steps correctly. Have a look here on how to Install SSL Certificate: http://www.geocerts.com/install/owa

[Aikonik]

see here for more suggestion : http://forums.techarena.in/server-security/385636.htm
http://support.microsoft.com/kb/239452