Ethernet wrapper IP core with ML403

Hello,

I would like to try the Ethernet Wrapper IP core together with the ml403 
board and I have a problem making it operational. I have generated core 
form generator after that update the constraint file so that all (I 
think) RXs, TXs and PHY reset nets are connected to the pads. After 
programing the FPGA I can see that PHY has been reseted and connection 
has been established but when I send  date to the board I have no 
respond. In the example design  which I'm using is loopback module which 
connects TXs lines with RXs and makes address swapping so I should get 
what I'm sending but in fact the board does not send anything.
Where I'm making mistake or what I haven't done which is necessary?

Regards,
Bartek