No Respone from Agent

[mmrd]

Dear Zabbix Community :-)

I am using zabbix server and multiple zabbix proxies. Last week one of me proxies crashed so I set up a new machine. But since then I get the well known error on the server webgui:
"Received empty response from Zabbix Agent at [AGENT_IP]. Assuming that agent dropped connection because of access permissions"

I only changed the proxy, nothing else.
Here is the config from the agents with this proxy:

Server=#IP_of_Server
Hostname=#ServerName
ListenPort=10050
ListenIP=#IP_of_Agent
StartAgents=5
DebugLevel=3
ServerActive=#IP_of_Server:10051
LogFile=c:\monitoring\log\zabbix_agentd.log

When I start the zabbix service on the proxy everything seems fine, proxy log:

6725:20150616:133149.370 Starting Zabbix Proxy (active) [proxy2-monitoring]. Zabbix 2.4.4 (revision 52341).
6725:20150616:133149.370 **** Enabled features ****
6725:20150616:133149.371 SNMP monitoring: YES
6725:20150616:133149.371 IPMI monitoring: YES
6725:20150616:133149.372 WEB monitoring: YES
6725:20150616:133149.372 VMware monitoring: NO
6725:20150616:133149.372 ODBC: NO
6725:20150616:133149.373 SSH2 support: YES
6725:20150616:133149.373 IPv6 support: YES
6725:20150616:133149.374 **************************
6725:20150616:133149.374 using configuration file: /usr/etc/zabbix_proxy.conf
6725:20150616:133149.424 current database version (mandatory/optional): 02040000/02040000
6725:20150616:133149.425 required mandatory version: 02040000
6725:20150616:133149.606 proxy #0 started [main process]
6731:20150616:133149.614 proxy #1 started [configuration syncer #1]
6733:20150616:133149.626 proxy #3 started [data sender #1]
6732:20150616:133149.628 proxy #2 started [heartbeat sender #1]
6734:20150616:133149.635 proxy #4 started [poller #1]
6735:20150616:133149.654 proxy #5 started [poller #2]
6736:20150616:133149.663 proxy #6 started [poller #3]
6737:20150616:133149.682 proxy #7 started [poller #4]
6738:20150616:133149.698 proxy #8 started [poller #5]
6739:20150616:133149.710 proxy #9 started [unreachable poller #1]
6740:20150616:133149.730 proxy #10 started [trapper #1]
6741:20150616:133149.751 proxy #11 started [trapper #2]
6742:20150616:133149.781 proxy #12 started [trapper #3]
6743:20150616:133149.833 proxy #13 started [trapper #4]
6744:20150616:133149.851 proxy #14 started [trapper #5]
6748:20150616:133149.888 proxy #15 started [icmp pinger #1]
6749:20150616:133149.924 proxy #16 started [housekeeper #1]
6750:20150616:133149.949 proxy #17 started [http poller #1]
6755:20150616:133149.964 proxy #19 started [history syncer #1]
6756:20150616:133150.000 proxy #20 started [history syncer #2]
6731:20150616:133150.012 received configuration data from server, datalen 61796
6760:20150616:133150.018 proxy #22 started [history syncer #4]

All my other proxies work fine. I testet network availability and ports.
I don't know what could be the problem.

I am using server, proxy & agent with version 2.4.4.

Can somebody help me?

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Edit:

I solved it. But I didn't really change too much. First of all I installed the proxy from start.
But same Problem.
Now I configured all parameters for the agent, still no change.
But as I configured the parameter for agent & proxy "ListenIP=" which is not mandatory it started working.