@Ollie not to worry! I hadn't had a chance to try again since my post. Although I have gone out and bought a normal IR LED since to try out incase I still have problems. So i'll have a try again tonight and post back how it goes.
@Gordon Thanks for the clarification. So I take it that IR LED is constantly shining the 38kHz frequency and the digitalPulse through the other pin is interrupting that at the scheduled times in order to actually transmit the signal?
If that's the case I was reading that diodes
In electronics, a diode is a two-terminal electronic component that conducts primarily in one direction;
Does that not mean the the 38kHz turning on and off is very weak?
Here are some other pictures from the documentation for the module incase you are interested. One shows it wired to output, ground and power of an Arduino :$