Arduino IDE problems

I am having issues with my Arduino Uno IDE. I am coding a flight computer, and it is going really well except for one problem. The Arduino IDE doesn't like to compile some void functions. I will call a void function, then later in the code will write out the void function. This works like is should except sometime when it doesn't. About 40% of the time, I will get an error message saying 'exampleFunction was not declared in the scope' even though there is actually the void function in the code. please help me, i am very confused. Sorry is this is the wrong place to post this question.