Exactly the same problem, and even if you do change the 'version check bypass' to "true" it still says there is a problem with the craftbukkit version - One is out of date . I'm Not sure where to get a previous version of towny which will work with the Craftbukkit that Tekkit 3.1.2 has, however, what i would do if i was you is get PreciousStones Instead, it is a similar idea apart from is less complicated.