it is utterly impossible to help you without seeing your Apache HTTP Server error_log on LogLevel debug and your EAP server.log on at least INFO. Apache HTTP Server log is more important though.
Furthermore, could you post your Apache HTTP Server mod_cluster and mod_proxy (if any) related configuration?
1.2.x is Deprecated
mod_cluster 1.2.x is deprecated. If you find a bug, it will be fixed in master and 1.3.x branch. We will do our best to help you with configuration on any version though.