ZBX_NOTSUPPORTED: Timeout while executing a shell script. - Timeout solution fails

[Ozcan]

Hello All,
I am new to zabbix but i searched a lot for troubleshooting some problems. Regarding to my problem :

There are 12 proxy servers, many windows and linux clients to monitor.. My problems is a classic ;

-We use IIS site & pool check template for windows servers and some of them shows :
ZBX_NOTSUPPORTED: Timeout while executing a shell script.

when i check this from proxy server and use command :

zabbix_get -s x.x.x.33 -p 10050 -k apppool.discovery
ZBX_NOTSUPPORTED: Timeout while executing a shell script.

Result is same obviously.. But on the client site script works well and shows pools and sites successly when i try manually.
Also there is another twin server of this one and it works successfully as well
zabbix_get -s x.x.x.32 -p 10050 -k apppool.discovery = shows the result (same site and pools on client) from proxy server.

Debugging on client doesnt show any different as well.. Except timeout..
I increased the zabbix front end server timeout value to 30, proxy server value to 30 and I dont get why 1 client with timeout value of 4 shows successful result but other ones config is increased to 30 but still doesnt work.
Plus i have many servers like that to test and some of them worked by increasing timeout value of the client config but others dont..
So this solution seems inconsistent for me..

Can you give any solution advice or where to check for problems ?

[Ozcan]

Any idea ? Anyone ? Is there any way to find exact root cause for custom scripts dont get items from discovery rules ? Logs dont seem to show any direction.