Ok, first off a couple things:
#1 - put your code in code tags if you want anyone to help. (honestly)
#2- I'm looking at this page:
http://www.cs.wisc.edu/~cs302/io/JavaIO_Scanner.html
Are you sure your defining custNum properly? I think when you get the user input, its going to be a string. You will need to convert it. Also where is it defined? Im not big on Java, but hope this helped. Last thing, are you getting any errors when you execute the code?