Hello Richard Leung,
Which is the exact version that you use?
It seems there is a problem with the generation of the dynamic assembly on your side. We will send you the assembly, once you let us know about your version. You can check it by following this KB Article: http://www.sitefinity.com/support/kb/sitefinity-3-x/how-to-check-your-current-sitefinity-version.aspx
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