Hungarian Mystery Stamp

Here is a stumper. I'm cataloguing my Hungarian stamps, and came across this one that I am not able to identify. It's printed on very thin paper. There is no notation of "Magyar Posta" on the stamp, although the denom. 1K, as well as the St.Stephen inscription would lead to believe it's Hungarian. I could not find anything similar in Scotts. At first I thought this might be a 'cinderella,' but then noticed the double cross watermark (WMK137) The 'Ba' in the bottom right corner looks to be part of a cancellation, although I cannot be sure. Any input from you experts out there would be much appreciated.

I don't have a Michel for Hungary or I'd probably find it. But the "Ba-" may be a misplaced version of the "Baranya" overprint found in Hungary back of the book in Scott.

It is described by this seller as a poster stamp and fundraiser:

http://picclick.com/POSTER-STAMP-SZ...8833127.html

thanks to both of your for your quick responses. Turns out this most likely is a poster stamp, although still not sure, because of the watermark, I wasnt aware they watermarked poster stamps, but also significant is that the stamp did not read "magyar post", thus causing me to wonder if this was not actually a genuine postage stamp. All the same, a very interesting finding. thanks again.
mike/fresno

It`s a revenue-stamp. Issued 01.04.1914. Wmk. nr. VII or VIIa (according hungarian catalogues- `double cross` standing or laying). Different paper types (thinner-thicker,but not catalogued). Perf. 12 or 11.5.