I now have the circuit working. I dont quite understand why the first attempt didnt work, but the following works for me. Thankyou for taking the time to solve my problem.

DEFINE OSC 4 ;WE ARE USING A 4MHZ XTAL OSCILLATOR

CLOCK VAR PortB.6 ;CLOCK SIGNAL IS ON RB6, PIN 12
DATAPIN VAR PortB.5;DATA SIGNAL IS ON RB5, PIN 11
FQUD VAR PortB.4 ;FREQUENCY UPDATE ON RB4, PIN 10

TRISB = 0 ;SET ALL OF PORTB AS OUTPUTS
PORTB = 0 ;SET ALL OF PORTB LOW

Pause 1000 ;WAIT FOR CIRCUIT TO STABILISE
PULSOUT FQUD,10 ;RESET DDS
SHIFTOUT DATAPIN, CLOCK, 0, [$DD, $24, $06, $01, $00] ;SEND SERIAL DATA TO DDS
PULSOUT FQUD,10 ;LOAD NEW FREQUENCY 500KHZ

SHIFTOUT DATAPIN, CLOCK, 0, [$DD, $24, $06, $01, $00] ;SEND SERIAL DATA TO DDS
PULSOUT FQUD,10 ;LOAD NEW FREQUENCY 500KHZ
;SERIAL DATA IS SENT TWICE, IF ONLY SENT ONCE DDS CHIP SOMETIMES LOCKS UP
END