Are you using ACadDoc.LSP or an MNL file?
If the ACadDoc.LSP is it on your support folder paths? What happens if you type this at the command prompt?(findfile "acaddoc.lsp")
If nil, the AutoCad can't find it, if it's shown in another folder, then you have 2 or more of them - AutoCAD only loads the 1st one it finds.
If the MNL is the accompanying CUI loaded? Are they both in the same folder and named the same?