VI only works if it is already open when TestStand calls it

[UnholyPenguin]

I have a VI that is taking waveform input and saving the image to file.

It only seems to work when I step into it or if it's already open when TestStand runs it.

Any idea why this is?

[Oli_Wachno]

Not working as in "does not show the front panel"?

[UnholyPenguin]

It doesn't save the image.  

I made another VI that seems to work as expected, the only difference that I can see is that it doesn't have a teststand object reference input and it takes longer to run