Are you greasing the pan the right way?
Bundt pans are notorious for sticking, if not greased right, especially fancy shaped bundt pans like Nordicware.
Are you letting the cake cool inside the pan? Thats a no-no, when it comes to bundt cakes. If you let it cool inside the pan, it can stick. Flip it onto a plate as soon as it comes out of the oven.
If you don't use the right way of greasing a bundt pan, it will also cause it to stick.
A dirty bundt pan will also stick, if all the previous cake grime was not cleaned off.
A "trick" I use for all of my cake pans..........
I put the pan in the freezer while I am making the batter.
When the batter is ready to pour, I take the pan out of the freezer and spray it with a thick coating of non-stick pan spray with flour in it. Then I pour the batter into the pan and bake it. It comes right out of the pan each time, no matter what kind of cake I am making in it, or how long it sits in the pan.