(R2k3)I cant import new chipsets/animation graphics/characters/(any new stuff)

So like I have been downloading a bunch of new things that I could put in my game but it's a huge hastle because eveytime I try to import it puts up a notice box that says like invalid bitmap image. I don't know wheather it's a wrong type of picture or if the beackround needs to be a different colour or any of that so please help!
And if it is any of the problems I noted then could you tell me how to do them
because I am partially new to this whole thing.
Thnx
oOTheKidsOo
 

the issue arises due to the color limitations of rm2k3.

I ran into the same problems, so I could never really customise my game...somebody else should know how to fix it, i never learned >.<

If it's colour limitation, are the things you're downloading DESIGNED to be used in RM2K3 or in RMXP?  If they're intended for RM2K3 then it should already be set up correctly.  You COULD try using some graphics program that will allow you to change the colour depth to a reduced range, but that'll very likely give you results that you aren't happy with.  Still may be worth a try.

you gotta make it the right colour graphics and image size!
All I did was export a Ex. char set and use paint to figure out the size for it, made a new page with that size and changed the colour to 256!