ofxMotionTracker doubt


I’m trying to use the ofxMotionTracker addon, I have the following:


#include "ofxMotionTracker.h"  
class testApp...{...  
    MotionTrigger motionTracker;  


#include "testApp.h"  
#define CAMERAWIDTH 320  
#define CAMERAHEIGHT 240  
void testApp::setup(){  
	motionTracker.init(CAMERAWIDTH, CAMERAHEIGHT, 0);  
	motionTracker.setOpticalFlowResolution(CAMERAWIDTH, CAMERAHEIGHT);  
void testApp::update(){  
        int x, y;  
	float u, v;  
	for ( y = 0; y < CAMERAHEIGHT; y++ ){  
		for ( x = 0; x < CAMERAWIDTH; x++ ){  
			motionTracker.getVelAtPixel(x, y, u, v);  

At the following line:

			motionTracker.getVelAtPixel(x, y, u, v);  

I get the next error:

error: no matching function for call to ‘MotionTrigger::getVelAtPixel(int&, int&, float&, float&)’

The signature of the method is like this:

void getVelAtPixel(int x, int y, float *u, float *v);			// takes coordinates in pixels   

How can I get vel of x (u) and vel of y (v)?

Thank you!