I can't find the problem, tried everything...wait what?!

Okay, So I had a problem on my server being able to place lava.
Once placed it disappeared, so I went to find the problem.
Checked essentials protect, checked WorldGuard, checked EntityManager and any other plugin I thought would disable lava from being placed. Nothing, there should be no reason lava can't be placed. So then I thought, maybe i'm just in spawn and can't place anything, nope, i'm not in spawn area and I can place blocks where i'm standing. Can't be because I don't have permission to place lava, i'm a OP.
So I did the next best thing, remove all my plugins and add 3 until I find the culprit.
On the first 3 I place..can't place lava? What the? The tree I placed were plugins that had nothing to do with world protection or block placement prevention?
Herochat...TelePlusPlus...and CraftBook...
I check anyway, nothing.
So I remove the 3 plugins, start up my world, and guess what?
I can't place lava! No plugins! What is going on?
So I check everything in the server folder like the "server properties" and what not, nothing to do with lava there.

So what is it that is going on, this is a big problem. I need help.

 

Can you place anything else?