Apparently the trading post has a bug :(

[Rubywinged]

Not a huge amount of neopoints but i lost 17,000 on the trading post. I bid on 2 separate lots one was in some other language so im unsure if they rejected the offer closed the lot or accepted another offer. But anyhow i believe i lost both trades to someone else. And my neopoints poofed. I got on and only have 3,000 when i know i bid 17,000 for both lots. I've reported this to TNT not sure if anything will be done to fix it but i thought i would warn others that apparently a problem exists so be careful if you are risking ALOT of neopoints out there!

[May]

We actually have a thread all about this over in Neopets Help, where the problem has been discussed for almost a month and a half

Here's the thread: click.