DllRegisterServer Entry point not found.

"DllRegisterServer entry point was not found".

This behavior may occur if you try to register a DLL by using Regsrv32 while you are logged on using an account that does not have administrative credentials, such as an account that is a member of the standard users group. An account that does not have administrative credentials cannot write to the registry or change files in the System32 folder.

The behavior occurs because Windows XP and Windows Server 2003 use a more restrictive security scheme than earlier versions of Windows use. This scheme prevents standard users from registering DLLs.
From: MSDN

It might not the right answer but you could take into consideration.

 Another suggestion is that copy it to another the program directly that your dll to register for and click to install it again..i.e.C:\WINDOWS\system32