Not authorized to perform: lambda:InvokeFunction

Hi,

I have a very fustrating problem, that I am able to use the function(create_user) with aws_cli, but in the iOS app always trhow an error of not authorized to perform: lambda:InvokeFunction.
Anybody know what could be wrong?
Cheers

Can you post a screenshot for what is thrown the error? Are you making an API request?