bandwidth adjustment for streaming video to server

I am trying to adjust for available bandwidth at a mobile device sending live video to a server. I am currently using the total upload bytes per second and the video loss rate as the parameters to detect when I need to change the camera parameters. I am using the video size and framerate to estimate the required bandwidth. (bandwidth = height * width * framerate / [encoding contant] )

http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/net/NetStreamInfo.html

When the available upstream network capacity is low, I adjust the maximum video upload bandwidth and the framerate for the reduced capacity.

http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/media/Camera.html

The problem I am having is that even after adjusting the camera parameters, the video loss rate can be very high ~0.6-0.7. This is even for values that seem to work normally if the camera is initially set with these values.

Can anyone explain why what causes the video loss rate to be high? I may need to use a different parameter to indicate when the camera parameters need to be changed.