Why do I get ipv6 test failed messages during building net-snmp on Red Hat Enterprise Linux 6?

Issue

• Unable to install Net-SNMP on REHL 6 machine while ipv6 is disabled. Installation will go fine if ipv6 is enabled. why?
• Found following error messages during building net-snmp using source rpm :

. . . . .
62:testing UDP6 Transport...(no pid file(s) found)FAIL
63:testing TCP6 Transport...(no pid file(s) found)FAIL
64:testing Unix Transport...ok
65:testing DTLS-UDP Transport...SKIPPED
66:testing ALIAS Transport...ok
Summary: 64 / 66 succeeded.
make[1]: *** [test] Error 2
make[1]: Leaving directory `/root/rpmbuild/BUILD/net-snmp-5.5/testing'
make: *** [test] Error 2
error: Bad exit status from /var/tmp/rpm-tmp.MfUEQV (%check)
RPM build errors:
    Bad exit status from /var/tmp/rpm-tmp.MfUEQV (%check)