this year my montana did not flower it went to seed any ideas why

I think we need a lot more description of what you mean by "it went to seed",

Since flowering and seeding are merely the earlier and later stages of the same process, it is hard without more detail to understand quite what happened.

By "montana" do you mean Clematis montana?

Yes I am also confused, in order to go to seed it has to flower to produce seed. more information please.