Afterburner Does Not Work

FS2004 on Win2k with NVidia Ultra 5600 and 256MB memory controlling with a CH Products Flight Yoke.
I have the thrusters set to my Z-Rotation (simply put, one of the throttle controls). I've never had a problem in the past, simply opened the thrust controls on a Jet (Gulf IV or Lear 45 as example), then used my mouse to pull the thrusters backwards to turn on the afterburners.
All of a sudden, when I pull them back, they pop back to idle. I can't get the afterburners to stay on. This is causing a problem on shorter runways or if I land a little long.
Any ideas what is causing this?
btw - I don't have the FS9 patch installed.
I have the thrusters set to my Z-Rotation (simply put, one of the throttle controls). I've never had a problem in the past, simply opened the thrust controls on a Jet (Gulf IV or Lear 45 as example), then used my mouse to pull the thrusters backwards to turn on the afterburners.
All of a sudden, when I pull them back, they pop back to idle. I can't get the afterburners to stay on. This is causing a problem on shorter runways or if I land a little long.
Any ideas what is causing this?
btw - I don't have the FS9 patch installed.