Receiving "only a variable can be connected to a process" error trying to add submodel

[dsinha]

Hello,

Since I am using multiple iterator tools, I had to split my model into submodels. But when I try to add the submodel to the main model, I get the error "only a variable can be connected to a process".

Here is the main model, with the submodel (Part II - 1) highlighted.

Here is Part II - 1, that I am trying to join to the mail model. The output from this would be a join table in the main model.

Any help would be appreciated. 

Thanks!