MPOS won't show miners I'm trying to setup private mining pool, took some time to go around lots of stuff but eventually I got stuck.

I have: a miner (locally), pushpool (ext server #1), MPOS - frontend (ext server #2) and a wallet (locally).

The miner CAN see pushpool, pushpool CAN connect to the wallet however MPOS shows there's no miners whatsoever.                                                                                                    

I'm not using that stratum-mining but as I heard, it's optional                                                                                                                                                      

cgminer was reporting that some block was found and as far as I understand it takes information about current block/diff from the wallet. If miner connects to pushpoold then the link between miner-pushpool-wallet must be appropriate, right?                                                                                                                                                                                                   

Thus I have no idea why mpos reports no active miners, JSON result for current stats is {"pool_name":"","hashrate":0,"workers":0,"shares_this_round":0,"last_block":null,"network_hashrate":43631019858}
I just ran into the same issue, although mine was a syntax error...Also you didn't specify what coin your mining. Different settings for different coins. Pushpool is responsible for inserting the share info into the SQL database. You need to add the following lines to your pushpool config in the database area:

        "sharelog" : true,

        "stmt.pwdb" :
          "SELECT password FROM pool_worker WHERE username = ?",

        "stmt.sharelog" :
         "INSERT INTO shares (rem_host, username, our_result, upstream_result, reason, solution) VALUES (?, ?, ?, ?, ?, ?)"


Sharelog must be true, not "true"(my syntax error that took 24 hours of hunting.) You need to add the "stmt.sharelog" entry and pushpool will insert the correct data. The MPOS or front end will pick it up instantly. The database table "shares" has 2 additional columns called difficulty and time. Don't worry about them. Difficulty has a default of 0 and time will insert the current timestamp as default. 

As for Stratum, the coin daemon must support getblocktemplate. I'm mining BBQ/BQC coin and it is not implemented yet. I am stuck using long poll and I'm getting alot of stales. Need to optimize for the coin your mining. It is working and I hope that pooler will release his fork of bbqcoind on github. He added getblocktemplate and it's working great at bbqpool.net. Happy mining!