Enable bits (IE), Interrupt Flags (IF) or Priority bits (IP).
Don't "mess" with them. That includes GIE and PEIE or GIEL.

Many interrupt sources have registers that affect the specific peripheral.
For instance ...
  • If you don't set TXSTA and RCSTA then you will never get proper interrupts from the USART.
  • If you don't set T1CON, you will never get interrupts from TMR1_INT.
  • And ...
    If you don't set the INTEDG bits, you may never get the correct interrupt from INT2_INT.

You have to tell the hardware how to handle the signals.
DT_INTS will handle the interrupts.
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