Rocksim says no motor mount

[CPA - not an Engineer]

I've seen this happen before, and ran into it again tonight - "In order to run simulations, at least one body tube in each rocket stage needs to be designated as a motor mount. Your current design contains no body tubes"

Except I'm using a Rocksim file for a Big Bertha that was downloaded rocketreviews.com. And it clearly has an 18mm tube that is marked as a motor mount. Does anyone know of a work around?

 

[Fattbank64]

Two items

1. Apogee has an Estes Big Bertha RockSim file on their website.

2. If the component doesn't show MMT, more than likely, it was designated as a 'Body Tube.' Instead, the part should be 'Inner Tube.' Then, select the Motor Mount option.