How to use the "Connect" tool in Simlab?

Hi everyone,
I am doing Hex meshing but the elements are not uniform between parts. I want to use the "Connect" tool in simlab to connect them and the number of elements on the same edge is the same in two parts. But when I select the object in " Connect" I can't " Apply" or " ok". So how do I use this tool?
The main part is the part pointed to by the yellow arrow
The subsection is the part where the blue arrow points to