tcp_test.stp failed to run in my IA64 box

["bibo,mao" <bibo dot mao at intel dot com>]

hi, 
   tcp_test.stp failed to run in my IA64 box, it can not resolve $return variant.
I simplified the test case like this
probe kernel.function("tcp_sendmsg").return {
        size = $return
        if (size > 0) {
                send_bytes += size
        }
}

The following the error compiling message.

Pass 1: parsed user script and 39 library script(s) in 463usr/4sys/468real ms.
parsed 'tcp_sendmsg' -> func 'tcp_sendmsg'
pattern 'kernel' matches module 'kernel'
focused on module 'kernel' = [a000000100000000-a0000001018f6f28, bias 0]
pattern 'tcp_sendmsg' matches function 'tcp_sendmsg'
selected function tcp_sendmsg
prologue searching function 'tcp_sendmsg' 0xa0000001004d51a0-0xa0000001004d7b60@net/ipv4/tcp.c:788
checking line record 0xa0000001004d51a0@net/ipv4/tcp.c:788
checking line record 0xa0000001004d51a1@net/ipv4/tcp.c:788
checking line record 0xa0000001004d51a2@net/ipv4/tcp.c:788
checking line record 0xa0000001004d51b0@net/ipv4/tcp.c:788
checking line record 0xa0000001004d51b1@net/ipv4/tcp.c:797
prologue found function 'tcp_sendmsg' = 0xa0000001004d51b1
literal_stmt_for_return: finding return value for tcp_sendmsg(net/ipv4/tcp.c)
literal_stmt_for_return: finding return value for tcp_sendmsg(net/ipv4/tcp.c)
probe tcp_sendmsg@net/ipv4/tcp.c:788 pc=0xa0000001004d51a0
pattern 'kernel' matches module 'kernel'
keeping expression operator '=' at 1.stp:2:7 because it writes: size and/or embedded: 0
keeping expression operator '+=' at 1.stp:4:14 because it writes: send_bytes and/or embedded: 0
semantic error: unresolved target-symbol expression: identifier '$return' at 1.stp:2:9
semantic error: unresolved target-symbol expression: identifier '$return' at 1.stp:2:9
semantic error: unresolved target-symbol expression: identifier '$return' at 1.stp:2:9
semantic error: unresolved target-symbol expression: identifier '$return' at 1.stp:2:9
Pass 2: analyzed script: 1 probe(s), 0 function(s), 0 global(s) in 254usr/22sys/278real ms.
Pass 2: analysis failed.  Try again with more '-v' (verbose) options.
Running rm -rf /tmp/stapupBbik
: