probably something simple I'm overlooking

I can't seem to figure out what I am doing wrong with passing the parameters between functions. I know that the calculations are correct (they are simple) and in the getTestScores function I went ahead and tested the calculations to make sure. It seems like the values for test1, 2 and 3 aren't being stored in memory as whatever I input gives a value of 0. getTestScores and displayAverage both need to be void functions and that's what I'm struggling with I think.

-------------------------Here's the code-------------------------

Code:

#include <iostream>
#include <iomanip>

using std::cout;
using std::cin;
using std::endl;
using std::fixed;
using std::setprecision;

//function prototypes
void getTestScores (double, double, double);
double calcAverage (double, double, double, double);
void displayAverage (double); //void function, no return value to main.

int main()
{

	//declare variables & initialize
	double average = 0.0;
	double test1 = 0.0;
	double test2 = 0.0;
	double test3 = 0.0;

	//call function to get test scores
	getTestScores (test1, test2, test3);
	
	//call function to calculate average
	calcAverage (average, test1, test2, test3);
	
	//call function to display average
	displayAverage (average);

	system ("pause");
	return 0;
}   //End of the main function

//*************************Function Definitions**********************

//Get Test Scores function
void getTestScores (double test1, double test2, double test3)
{
	cout << "Enter the first test score: ";
	cin >> test1;
	cout << "Enter the second test score: ";
	cin >> test2;
	cout << "Enter the third test score: ";
	cin >> test3;
}	//end of getTestScores function

//Calculate Average function (return average value)
double calcAverage (double average, double test1, double test2, double test3)
{
	average = (test1 + test2 + test3) / 3;
	return average;
}	//end of calcAverage function

//Display Average function (double)
void displayAverage (double average)
{			
	cout << "The average of the three scores you entered is: " << average << endl;
}	//end of displayAverage function

Any help would be greatly appreciated by this noob!

where does the return of calcAverage go?

getTestScores is being called with parameters "by value" (aka, copies), not "by reference".
As a result, you're not changing your values in main.

argh, I figured it out. Had a couple of issues actually and taking a break and coming back to it it was obvious.