Are you setting this statement to true?
if (false && (block.GetHash() != hashGenesisBlock))
There is a section of code deliberately missing from main.cpp on a lot of coins to prevent people from trying to generate a genesis block. See this page to get an idea from Litecoin's example:
https://gist.github.com/dmikey/8359944. This can be applied very easily to other algo coins.
If you're using X11/X13/X15 etc the guide you're using is rather outdated and once the genesis block has been created, it happens instantly so don't expect to wait a while for the machine to churn out a load of spam in the debug.log file, like it used to. The genesis block is easily overlooked if you are expecting something else to happen.