Network tables not syncing?

[BitTwiddler]

Yesterday we were testing our boulder shooter. We use a motor and we want to control the motor speed using a slider control on the custom tab of the LabView dashboard.
We noticed some strange behavior using this control which I assume is using network tables to communicate with the robot. When we first start the driver station and the robot the speed control would work perfectly to modify the motor speed but then after trying new speeds it would suddenly no longer update the speed setting on the robot.
We looked at the variables tab on the dashboard and we could see the speed control variable following the slider setting but when we probed the same variable on the robot side it would not change. It seems like that variable stopped getting updates on the network table server. The NT connected indicator on the dashboard is lit solidly green.
I am not really all that familiar with the network tables to do any really in-depth troubleshooting of this problem.
Any ideas what we should look at next? FYI, the game controller data is getting to the robot OK.
Thanks,
Dave