I was not able to run your VI because I don't have that instrument driver or instrument, but I can give you some pointers.
First off you are not using the error clusters correctly. Notice that you have not wired the error out from the VIs to anything. So there is actually no way to know currently if you are getting an error. You need to wire the error out from 1 VI into the error in of the next and so on and so forth.
Another comment is that when you tried to wire the error cluster and the instrument handle into the shift registers you missed. So notice that there are normal tunnels over lappping the shift registers, so the code is not using the registers. I would suggest deleting the tunnels and then re-wiring to make sure the error and handle go into and out of the shift registers.
