Error in Kernel Compilation

[Amrinder07]

hi i need to compile a kernel of Ubuntu from source code, and i had downloaded code and compile it

after some time it gives error from directory

/net/ipv4/netfilter

Error is :

CC [M]  net/ipv4/netfilter/ipt_ecn.o
net/ipv4/netfilter/ipt_ecn.c: In function âset_ect_ipâ:
net/ipv4/netfilter/ipt_ecn.c:33: error: âXT_DSCP_MASKâ undeclared (first use in
this function)
net/ipv4/netfilter/ipt_ecn.c:33: error: (Each undeclared identifier is reported
only once
net/ipv4/netfilter/ipt_ecn.c:33: error: for each function it appears in.)
net/ipv4/netfilter/ipt_ecn.c: In function âecn_tg_checkâ:
net/ipv4/netfilter/ipt_ecn.c:105: error: âXT_DSCP_MASKâ undeclared (first use in
 this function)
make[3]: *** [net/ipv4/netfilter/ipt_ecn.o] Error 1
make[2]: *** [net/ipv4/netfilter] Error 2
make[1]: *** [net/ipv4] Error 2
make: *** [net] Error 2

Please tell me what to do next.......please reply fast i need to submit it tomarrow