I had to change my invocation name, because I got some issues when I submitted it for certification. I rebuilt my skill after changing the invocation name, but when I was testing it, the new invocation name was not working, and I realised that my skill was being launched with the old invocation name, instead of the new one.
Rebuilding is not the complete solution, if you contact Amazon support, they would tell that your skill is using the new invocation name, because it's right. The hack for making changes to take effect is to rebuild your skill, switch off "Test is enabled for this skill" on test tab, and then switch on again. After this, the skill will be using the new invocation name while testing it.
I friend of mine had the same issue, and this solved it.