SSRS 2008 Error Message. What does it mean?

Anyone have a clue what this error message means?

An unexpected error occurred while compiling expres开发者_如何学Csions. native compiler 
return value ‘128’

128 Error Activation Report Server Reporting Services components from different editions cannot be used together.

http://technet.microsoft.com/en-us/library/ms165307.aspx