I have a doubt:

I already have ripple configured to trade.

There is an Bid of 6000 XRP, an Ask of 6400 which leads to a 400 spread (not real quotes, just an example)

If I want to buy BTC, I put 1 BTC x 6005.
The Bid climbs to 6005.
But... it stays there... then, someone puts a Bid for N BTC @ 6006 and I get to second place.
Why?

Can someone please enlighten me on this subject?