IP binding before sendto()

Dear all

I tried to channel IPv4 unicasts through a particular network
interface in my linux machine by binding the datagram socket to a
particular IP in the interested network interface. But even then it is
found to flow through both interfaces when used bind() just before
sendto().
Why this happens? . I am working on RedHat Linux Version 7.2 with
packages gcc version 2.96, glibc2.2.4-13 and glibc-devel-2.2.4-13. do
you have any idea why this happens?

Please help me

Thanks for all replies
Vinod Kumar P