I use mine without the GV-Net but it's a similar item so no issue there! My advice is to trouble shoot the item 1 by 1.
1. Is your com port functioning?
2. Could the Vido be defective? Try using a different DVR to test it if possible.
3. Also, the Geovision is a bit sickenening when it comes to setting the PTZ.
If I remember correctly there is 2 steps instead of 1 to do a simple thing! But I don't really remember because I help out a dealer of mine who bought a VIDO from me.