XF4 not working with a DUO X

Hi, I have a XF4 connected to a DUO X, but get no connection in the Browser (Chain Control). Both are with latest fw and the connection with ethernet cable is from DUO to XF4 main plug. The XF4 shows on the display after the initialization infos “FOOT #1”…“FOOT #4”.
Any ideas whats is wrong?