Sitl on windows: mavproxy say "No link"

I followed the guide to install the SITL on windows.
When I wrote the command “sim_vehicle.sh -j4 --map”, mavproxy started,
but he can not communicate very well with SITL.
Mavproxy initialize itself very slowly and writes continuously “link 1 Ok” and "link down 1"
One line every 2 seconds.
Thank you