I don't know why SELinux problems seem so frustrating. The problem almost certainly is related to the fact that there is frequently no error message. This is exactly the problem I ran into while turning up a new Apache web server on Red Hat Enterprise Linux 6 (RHEL6) with SELinux enabled.
The problem is that SELinux prevents Apache from making network connections by default. This is defined by the SELinux boolean
httpd_can_network_connect_db. In order to change this value, issue the following