LV Version/Runtime Question (working with LV 8.2.1 -- problems with a VI that was original build with LV 7.1)

Question

Hi there,
currently i have a strange problem and i hope some of you can help me.
Ok first i explain my situation:
My task is to expand a old testsystem that was written with LV 7.1.
During the time they began to work with LV 8.2.1 and saved the testsystem-VI with the new LV version.
Ok now my problem:
I have added some SubVIs (build with LV 8.2.1) to the testsystem which open a connection to a DUT (device under test) via fbus, usb or bluetooth (the drivers are designed for .net). But i always get a strange error message when the subVIs try to open the connection ("...Please check your connection string..").
First i checked the handover of the variables in the testsystem but found no mistakes. I also tested all SubVIs seperatly with TestVIs and they worked perfectly!!!
My question:
The main VI was original build with LV 7.1. Could it be possible that LV uses an old or several runtime engines to execute my testsystem which causes such strange problems (For me its the only logical explanation why it works with my Test-VIs but not with the testsystem)?  
But maybe you know more about such problems
Greetings, wonx

Answer 1

Hi wonx,
it's really hard to say what might be the problem without knowing your project.
Have you already performed a mass compile in LV8.2? If not, I would suggest to do so. Please see following link for an explanation of how the mass compile option in LabVIIEW works.