Why can I get internet signal in every room except one?

My local library is divided into multiple rooms, with both an upstairs and a down-stairs. It has wireless internet through-out the entire building except one room on the upstairs floor, the 'meeting room'.

The room isn't tucked away at the back of the building or anything, in fact it's the 1st room at the top of the stairs! There are rooms which are farther away (and around more corners) from the router but the internet signal is perfect in every other room, except the meeting room!

Somebody who works there told me that they even had some type of engineer out to figure out why there was no signal in that room but couldn't figure it out!

Mobile/cell phones work perfectly in the room and Mobile internet (i.e., the internet on your phone) works fine too! But for some reason we can't connect iPads to the library's internet in that room (we didn't try a PC or laptop, we only tried with iPads)

Could high voltage cabling behind the walls be affecting the signal -- or some other type of environmental factor?

Or could this be an iPad specific problem?

Any suggestions as to why this is happening?