I don't know if this has happened to anybody else, but my Platinum doesn't like the GTS for some reason. Every time I seek a Pokémon and have the one to trade for it, I can't trade. Has this happened to anyone else? Did it change from D/P to Pt? If anyone can help, please and thank you.

Thats odd...are you getting an error code with it or is it just saying "Communication error"?

No, none of that. It connects perfectly. It does everything it should let me do except trade. I shall give an example:
So I'm wanting to get this Uxie. The other party wants a Froslass. I press A and say I am willing to trade, and it takes me to my boxes. I go to Box 1, where my Froslass is stored, and I go and press A. The game goes *tink* like it would normally, but no menu pops up. I'm also pretty sure that the Pokémon you are supposed to trade is supposed to not be black-tinted, which mine is. I just don't know what is happening.

Sounds very odd. It's black-tinted if it doesn't meet the credentials defined.

Your pokemon probably isn't a high enough level

There is no defined level for what I am trying to trade, unless it's not showing me what level they want.

That's never happened to me before, are you sure you check everything? Can you at least trade other pokemon?

Is it the right gender? Was it haxx'd? Are you sure they wanted a Froslass?

It is the right gender because Froslass is only female. I didn't hax, and the Uxie didn't looked haxxed, and I'm sure they wanted a Froslass.

I've had this problem before. It was a Kadabra for an Abra, but I couldn't select the Abra in my box.

Platinum doesn't show what level they want for it, it annoys the crap out of me too. (cept I shouldn't complain... what asking for lvl 100 unown...)