Extern not working?

[ILBS]

=================================NewUnit_0.h
extern unsigned int *Xc, *Yc;
extern unsigned int t, u, a, b;


=================================Main.c
#include "abc_objects.h"
#include "abc_resources.h"
#include "NewUnit_0.h"

void main() {

Start_TP();
Xc = 1;
Yc = 1;

while (1) {
Check_TP();
GetCoordinates();
}
}


===============================abc_events_code.c
#include "abc_objects.h"
#include "abc_resources.h"
#include "NewUnit_0.h"


Xc = 0; //&a;
Yc = 0; //&b;


void GetCoordinates(){

//Xc = 0; //&a;
//Yc = 0; //&b;

if (TP_TFT_Press_Detect()) {


if (TP_TFT_Get_Coordinates(&Xc, &Yc ) > 120) {
t = *Xc;
u = *Yc;
ProgressBar1.Position = 180;
}
}
}

Code generates errors

All help appreciated