If you suspect you may have an evaluation version of Archive registered on your server, you can verify this by checking the saarch.dll file properties. Locate the saarch.dll file, right-click, choose "properties", select the "version" tab and check the "Description" label value. The evaluation version will read, "Archive(tm) (Evaluation)".
If you are running the retail version, then take the error message you have received at face value. Check for path or file name typos, file permissions and so forth.
If you discover you are running the evaluation version of the file, unregister this file and install the retail version of the product. If you are a license holder of Archive or FileUp, you will be able to download a new installation package from the updates page: http://support.softartisans.com/update.aspx
For the first week of the FileUp 5.0.11 release, an evaluation version of Archive was packaged in the retail installation package of FileUp. This has been corrected. If you obtained an evaluation version of Archive through this install package, you may download another copy of the 5.0.11 release and follow installation instructions as if you were upgrading.