How to use ADuC812 SPI

Hello!
I tried to use the on-board SPI of the Analog Devices ADuC812
but I didn't managed it to work. No Data, no SCLK, the Pins
seemed all to be dead at all.
Maybe one of you can give me a hint or working sample code.

Thanks.

Here's some of my code:

// Initialize the SPI Interface

SPICON = 0x37;// configure SPI port for: 0011,0111 = 0x37
// Fosc/64, CPHA=1, CPOL=0, master
IE2 = 0x01; // enable SPI interrupt

EA = 1; // enable interrupts

...

void send_SPI(unsigned int byte)
{
SPIDAT = byte; // trigger data transfer
}