BGP: can't set sockopt TCP_MD5SIG 0 to socket 16

Hi all,

I got four FreeBSD router and two of them using FreeBSD 6.1 Prerelease and
quagga 0.99.3 and the other two is using FreeBSD 5.4 with quagga 0.98.5. I
try to implement IBGP session in this 4 router and I encounter this problem
when activate the IBGP;

Info:
1) Two router is a Core - each has different version of OS and Quagga
2) Two router is a Distribution -each has different version of OS and Quagga

BGP: can't set sockopt TCP_MD5SIG 0 to socket 16
BGP: can't set sockopt TCP_MD5SIG 0 to socket 15
BGP: can't set sockopt TCP_MD5SIG 0 to socket 18

FYI, I've already compile quagga with MD5 patch for BGP. Thanks a lot.