Cisco Switching/Routing :: WS-C3750X-48 Dscp Removed On Router Port

I have a problem with dscp preservation on a WS-C3750X-48 catalyst; in my little diagram, his name will be SW2, so I have this:SW1 <-> SW2 <-> RT1. some phone connected to SW1 mark with dscp EF (46) the voice traffic.The "mls qos" was enabled on SW1 and SWt. The interlink switch ports has the "mls qos trust dscp" option, the phone port and the router port also.And the problem is I can see the dscp marking on the SW2 when I span the voice vlan on this switch but the dscp was removed ( DSCP set to 0) on the router port ( span on the router port for look )If I made also a packet capture on the router RT1, I see the DSCP was effectively reset to zero.If I disable the "mls qos" on SW2, of course all is fine and the dscp was preserved and forwarded to the router. [code]