vmotion won't work when when vm machine is runing

Hi,

I am trying to test my VMotion in a lab environment but it doesnt seem to work when the VM machine is runing.

when I shutdown the VM and try to migrant it manually then every thing seems to work just fine. but when the VM is runing and I try the same thing as before then the migration start and after 14% get stack and a general error appear." The vMotion migrations failed because the ESX hosts were not able to connect over the vMotion network. Check the vMotion networksettings and physical network configuration"

I need Help,

Michel vaillancourt