Tao Framework .dll import problem

Hi, I have a problem with importing a .dll file to my project. I’m using Tao Framework on a Windows Vista OS but when I try to load the file I get the following error:
OpenBVE
Unable to load ‘SDL.dll’: The specified module could not be found. (Exception from HRESULT: 0x8007007E)

If anyone has already successfully resolved this kind of a problem I would greatly appreciate any advice.
Thanks very much in advance.
