A few posts that suggest the same solution, instantiating the actual OLE class version (in their case, Outlook.Application.11) instead of the generic Outlook.Application
http://www.foxite.com/archives/outlook-automation-fails-0000116266.htm
http://www.tek-tips.com/viewthread.cfm?qid=1566343
http://www.tek-tips.com/viewthread.cfm?qid=1566343

>The error message is "Class definition 'outlook.application' is not found".
>
>>Do you get an error message?
>>If Outlook is already running when you attempt to instantiate your object, and the error message is something like "RPC server unavailable", then it might be an issue with user privileges ; your application is running with different privileges than the running Outlook instance.
>>
>>>I have seen messages about this before, but can't find them. On some machines lo = Createobject('outlook.application') fails, even though Outlook 2010 is installed. Any tips?