PIC16f877 Interrupt with IAR Compiler

Hi, I'm trying to write a ISR for this PIC, but i'm having trouble with IAR Compiler. The example codes that i'm testing compiled with errors.

I'm trying to compile the example given here
PIC microcontroller interrupt tutorial

The warning says: WREG, PCLATH, STATUS/ALUSTA and BSR will not be saved automatically unless a vector is assigned to the interrupt function.

How should I solve this?

Thanks

[Solved]
I didn't define a interrupt vector, that's why the warning...