USB device shown in NI-MAX, but SOMETIMES VISA Resource name in LabView shows nothing but refresh

[diegogg]

Ok so this is the problem

Im communicating labview with a MCU using USB Port. The device is recognized in NI-MAX when i plug it in but sometimes it won't show in VISA Resource name,for example last week it worked but today it doesn't

Then i open an old VI which i have on my pc, if i run it, close it, and open again from labview project directory the one i really want to work, then the problem its solved. The device its shown and the communication works. But lets say that for example I close labview, and open the VI from my desktop, again the refresh problem..