Problem with Discovery

[Spix91]

Hi everybody.
I was trying Zabbix to autodiscovery some new nodes in my university's network. Unfortunatly, when I try to set a new discovery rule, in Configure->Discovery, it gives me an error; "AJAX request error".
Actually, I don't know if I'm doing something wrong or if It's a bug. Can someone please help me? The ICMP Ping works perfectly, but nothing else is working. Maybe I'm missing something? Sorry but I'm not expert with Zabbix. Here's a screenshot of the error (Hoping I can't post it. Sorry if not).
Also, it gives me another error. mysql_connect(), as you can see from the image. Right now I just want to solve the Ajax error. Hope someone can give me a hand. Thanks in advace

Also, forgive me for my english. I'm Italian

*Mod, please, excuse me if the URL is not valid. If necessary I will upload the image in another host*

https://drive.google.com/file/d/0B63v9r8fU_thWXdtVER0UEFNNG8/edit?usp=sharing

[Spix91]

Up?
Can't anybody help me please?

EDIT: I solved the problem. I reinstalled the whole zabbix from source and it worked. Maybe I did something wrong during the configuration. Mod can close this thread. Thanks