can't create directory with File System component

hi,

I'm trying to create a directory like this:

if (fcheck ("F0:") != fsOK){
        //error, format
        fformat ("F0:", "/FAT32");
        //check, if not trwo an error
        if (fcheck ("F0:") != fsOK)
                fatalError(D_FATALERROR_FLASHDRIVE);
}
if (ffind ("F0:\\FTP", &info) != fsOK){
        fstatus = fmkdir ("F0:\\FTP");
        if (ffind ("F0:\\FTP", &info) != fsOK)
                fatalError(D_FATALERROR_FLASHMKDIR);
}

But when read the fstatus from fmkdir the answer if fsUnsupported... why?
I'm using a nor flash memory of 2 mbit, can write files but no to make a folder??

Thanks