Thread:Extension talk:Semantic Maps/special page error

When I try to go to the special page after all the necessary upgrade, I got this:

Fatal error: Class 'SMFormInput' not found in /home/.../transitunlimited.org/extensions/SemanticMaps/Services/GoogleMaps/SM_GoogleMapsFormInput.php on line 18

I think I had the same issue when I tried version 1.5, which was fixed.