If you don't spell the name of the script correctly, then SQL Plus will throw an error.
As you probably guessed, I'm trying to be funny. Without you providing information about the error being thrown, we have to guess at it. There's a pretty wide area for guessing!
Please be more specific. Cut the error message from the log (SQL Plus output) file, and post it here. If possible (without security or related problems), cut the whole command you are using, and post that here too.
With all of the people that contribute here, I'm sure that someone can help you if you can give them the information that they need to do that!