upstream RPC error

Hi there.
i try to setup pushpool + bitcoind. but when i connect to pushpool with cpuminer i receive the error:
[2013-04-21 12:47:47] json_rpc_call failed, retry after 30 seconds
[2013-04-21 12:48:17] JSON-RPC call failed: {
   "code": -2,
   "message": "upstream RPC error"
}
[2013-04-21 12:48:17] json_rpc_call failed, retry after 30 seconds

i see such error in pushpool server log:
root@:/usr/local/sbin# ./pushpoold -E -F --config=/usr/local/sbin/server.json
[2013-04-21 09:44:41.680413] Listening on host :: port 8336
[2013-04-21 09:44:41.680620] Listening on host :: port 8332
[2013-04-21 09:44:41.696668] initialized
[2013-04-21 09:44:46.196455] HTTP request failed: The requested URL returned error: 500
[2013-04-21 09:45:16.342902] HTTP request failed: The requested URL returned error: 500
[2013-04-21 09:45:46.503039] HTTP request failed: The requested URL returned error: 500
[2013-04-21 09:46:16.654475] HTTP request failed: The requested URL returned error: 500

bitcoind config:
^{testnet=0
server=1
rpcuser=username
rpcpassword=password
rpctimeout=30
rpcport=8335
rpcconnect=127.0.0.1
rpcsslciphers=TLSv1+HIGH:!SSLv2:!aNULL:!eNULL:!AH:!3DES:@STRENGTH
rpcsslcertificatechainfile=server.cert
rpcsslprivatekeyfile=server.pem
gen=0
keypool=256
paytxfee=0.00}

pushpool config:
^{{
   "listen": [
   {
   "port": 8336
   },
   {
   "port": 8332,
   "protocol": "http-json"
   }
   ],
   "database": {
   "engine": "mysql",
   "host": "localhost",
   "port": 3306,
   "name": "bitcoin",
   "username": "***",
   "password": "***",
   "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 (?, ?, ?, ?, ?, ?)"
   },
   "pid": "/tmp/pushpool/pushpoold.pid",
   "forcehost": "localhost",
   "log.requests": "/tmp/pushpool/request.log",
   "log.shares": "/tmp/pushpool/shares.log",
   "auth.cred_cache.expire": 75,
   "rpc.url": "http://127.0.0.1:8335",
   "rpc.user": "username",
   "rpc.pass": "password",
   "rpc.target.rewrite": true
}}

i have tried to change ports, reboot server. i found some posts here about such issue but they did not help me.
i can give you any logs. if necessary i can give ssh access to server.
  Thanks in advance.