Interface Free/Bond Choice is grayed out

[sstresau]

I'm trying to get an assembly running in Mechanica. I'd like to "bond" the parts together with a bonded interface. However, when I open the Interface Definition dialog box to make a new interface the Type is stuck on free -- it is grayed out and I am unable to change it to bonded. Anybody know why and/or how to make a bonded interface.

 

[sstresau]

After calling PTC help, I realized that the way to get a bonded interface is to define no interface at all. I was trying too hard, I guess.