Using same variable in Header and Source file

Hai,
I am using PIC16F development board, Mplab X IDE v4.20 and XC8 compiler.
In source file
range=1;
i want to check the value of 'range' in header file. for this purpose i declared like
extern int range; in header file. But it is giving error.

:0: error: (499) undefined symbol:
_range(dist/default/production\Digas.X.production.obj)
(908) exit status = 1

make[2]: *** [dist/default/production/Digas.X.production.hex] Error 1
make[1]: *** [.build-conf] Error 2
make: ***...

Using same variable in Header and Source file