Openwrt Raspberry Pi 2 image setuid syscall not working

Hi All,

I was trying to use run a program on my Raspberry Pi 2 which has been flashed with Openwrt 18.06.2 image. Everything works fine, but when the program tries to call a syscall "setuid", it fails with error "function not implemented". I am not sure why this is happening and want to know how can I get it working ? Do I need to rebuild the image with certain configurations ? Please point me any direction,. thanks,

Plus, I verified the CONFIG_MULTIUSER=y in the kernel config, so the syscall should not be disabled ?