can't connect to a certain wireless network

I canconnect to my home network, I can connect to the grocery store wifi, but when I try to connect to the school's wireless using the 13 character password that the tech guy typed in, I get a a screen and no matter what I clcik, the screen just pops back up. Other teachers have an ipad and can connect fine. What is happening. I called support and they just keep saying I understand that you are ........ I'm going to put you on hold.... I was on for over 1n hour trying to rectify it. I went back to the Apple store where I purchased it and it connects fine to their wifi. What do I need to do.