Because that is the offer and demand in that exchange. May be due to the low volume. Anyway it could make a great arbitrage opportunity so why you don't just take it?
I didn't "just take it" because
1. I'm new to all this...about "3 weeks old"😀.
2. I noticed it was a Asian market and in my 3 weeks I've read that many non-Asian country account holders seem to have problems with their transactions. Especially those transactions that are in their favor.
3. Refer back to #1
Thanks for you reply though!