Okay, I just tried uploading it again and this time I got a E-mail from avsim that they received it. Last time I didn't, so I must have done something wrong.
Edit the altitude of the AFCAD file in AFCAD 2.21 only, not in the other program you are using.
Could be a mesh issue. Slew to the center of the base, press Shift+Z and read the altitude off the display. Open AFCAD 2.21 and go to KLSV. Right click on the afcad to bring up the properties box for the KSLV file. Compare those two altitudes. If they are more than 1-2 feet off, you will need to either create a flatten file or raise the elevation of the afcad. When you raise the afcad's elevation, don't forget to change that figure in any traffic files that use KLSV, also change the elevation in the Runways property boxes.
Give that a shot and see what you come up with.
There are so many different mesh sets available, it's next to impossible to create a scenery these days that will work with 100% of the users out there.
Also, just a question, are you using the Las Vegas Photoreal scenery from Blue Sky?