External Insert and FX Chain

Hey all

Did a search but couldn't find info. Can anyone help me out?

I'm using external inserts to route out to some of my favorite hardware units while mixing in X2 producer. 

When I place the external insert into the FX bin. No problem and works great. 

In the Prochannel FX chain I cannot select external inserts. I can however drag it from the fx bin and place it into the FX chain. But when I do that it apparently stops sending signal from Sonar to my sound card. 

Is there a way to use an external insert in an FX chain? 

Not the end of the world if I can't but it would be extra nice to place inserts in a pickier way within my signal flow. 

Thanks