Problem with TEH's format buttons acting as submit button

I have a strange problem with Textile Editor Helper.

I have installed what is needed to work and my textarea is being
‘textilized’ (as I write Textile markups directly by hand).

However, when I click on any of the format buttons, bad surprise
appears: they act just as “submit” buttons! I have been trying to cut
some parts of code linking prototype as the only library, etc. - nothing

What could be the reason of such behaviour?