You've come to the right place! Can you upload your model to a drop box for us to review? OpenStudio categorizes equipment by control type (heating / cooling / uncontrolled) to locate it on the appropriate equipment list. The most likely scenario is that a particular type of component was allowed on the plant but not categorized for an appropriate equipment list.

Update

I received your model and found that "Plant 2" did not have any supply equipment.

I took a guess and figured that you wanted that heat exchanger to draw heat from one of the other hot water plants, so I rearranged things so that the heat exchanger is a supply component on "Plant 2" and a demand component on "Plant 1". I also found that your pumps were located on the demand side of the plants which is incorrect, unless you were trying to do a primary / secondary setup, so I moved them to the supply side. It now looks like this.

I didn't investigate your control options, so I can't guarantee that this is running exactly the way you want it to, but this should get you on the right path. I'll send the adjusted model back through email.