Oleg was right.

Wrong enable bit set ...
Corrected an retested the code.
No IRQ yet ... none what so ever ...

isr routine looks like this :

void spi_isr (void) interrupt 10
{
LED_R = ON; // turn red led on on any IRQ from SPI
transmit_done = 1;
switch (SPSCR)
{
case 0x80:
serial_data = SPDAT;
transmit_done = 1;
break;
case 0x10:
break;
case 0x40:
break;
default: break;
}
}

Any hints left?

PS.: I quote a piece from the datasheet page 151

Introduction The Can Controller has a total of 10 interrupt vectors: two external interrupts (), three timer interrupts (), a serial port interrupt, a PCA, a CAN interrupt, a timer overrun interrupt and an ADC. These interrupts are shown below.

It does not mention the SPI interrupt?????
The schematic figure includes the SPI at IEN1.3 and the EA at IEN0.7 ??????