rear of the vehicle won't lift. on 2001 Lincoln Navigator

Rear of the vehicle won't lift. Checked air suspension switch under dash, switch was on. It may be up at one point, but as I start to drive, it drops. It's low again once I get to my destination.

Asked by for the 2001 Lincoln Navigator
Have the air bags checked for leakage
Thank you so much for your quick response. I will do that.