J9137A Switch 2520 8-POE routing issue ?

Hi every body ,

I have a routing ? problem with a HP J9137A Switch 2520 8-POE.

When I set the IP ot this 2520 as gateway on every machines connected to it, they are enable to reach the Internet, nor I can access to them from the Intranet.

But I can ping them from the switch, and they can ping the switch. When I try a traceroute, I get nothing.

This is the topology :

                                                    .-,(  ),-.    
                                                 .-(          )-. 
                                                (    internet    )
                                                 '-(          ).-'
                                                     '-.( ).-'    

                                                         ^
                                                         |
                                                         v
                                                      ______ 
                                                     |_ooo_°| Modem

                                                         ^
                                                         |
                                               __________v__________ 
                                              |___|___|___|___|___|_|
                                              |_|___|___|___|___|___|   Firewall (192.168.0.254)
                                              |___|___|___|___|___|_|
                                                         ^
 .-,(  ),-.            MPLS (192.168.0.252)              |
(          )-.              __________              _____v____ 
  INTRANET    )  <----->   [_...__...°]    <-----> [_...__...°]  HP Procurve 2520 (192.168.0.253)
(          ).-'                                          ^
  '-.( ).-'                                              |
                                                         v
                                       ____   __     ____   __     ____   __ 
                                      |    | |==|   |    | |==|   |    | |==|
                                      |____| |  |   |____| |  |   |____| |  |
                                      /::::/ |__|   /::::/ |__|   /::::/ |__|

Yet, I added route like these :

ip route 192.168.1..0/24 192.168.0.252
ip route 192.168.2..0/24 192.168.0.252
ip route 192.168.3..0/24 192.168.0.252
ip route 0.0.0.0/0 192.168.0.254

But none worked.

Thanks for any help.