Openssl 'error reading input file'

Hi guys, I’m really sorry to be a pain, but this is starting to wear me down…openssl enc -aes-256-cbc -d -a -pbkdf2 -in myfile -out newfile.
All I get is ‘error reading input file’. If I leave out -a, then I get ‘bad magic number’. It’s the same if I include -base64. I’m about ready to pull my hair out…as if I don’t have little enough as it is!!!
Please help guys.