If you're using version 4.1b (not on this site) you don't need the common key. If you're using the version in the OP, you have to provide the key as a binary file, not a text file. Paste the key into a Hex Editor like HxD so it is the actual binary of the key instead of the hex character representation. If you pasted the key into notepad, you've made it incorrectly.
If you already have python installed on your machine, you could use that instead of HxD. (quote has been modified to reflect ckey.bin instead of disckey.bin)