Foot Lok Stop Tub Drain

I purchased one of the big box store Foot Lok Stop Tub Drains, the push down type. I removed my current 1 1/2 stopper. When I screw in the new Foot Lok Stop Tub Drain I get two or three turns and it will not screw in any further. Both stoppers, old and new are1 1/2 drains. What am I doing wrong?

Thanks in advance

guys, I edited my post and made some corrections. I hope this makes my problem clearer.

IF both have the same thread size then it should not happen. Just because both are 1 1/2" does not mean the manufacturers used the same parts.