Some won't install!!

I have DL'ed several planes and installed them sucessfully but some will not. When trying to extract files to the FS2002 directory it says "this file already exists, do you want to replace?" whether I say yes or no it wont work. Whats up? Thanks for any help!

After you have d/loaded and unziped make sure it has not got two folders.
So say you had d/loaded a 747 make sure the folder when you open it has a model,panel,sound and texture folders........and not another 747 folder then the others
Or just rename it eg 747aa

Hope it helps