Cleat Issues!!

Morning all, as i'm pretty much a clipless virgin I could do with your help..! Last night on my commute home I really struggled, let me rephrase that, couldn't, clip into my left pedal. Now, as someone who is getting used to the clipless way having my left foot constantly out inspired little confidence though when pulling away from traffic lights up a hill it is difficult to get going as my foot kept slipping off the pedal..

I White Lightning'd the cleats when i got home and will try any other tips when I get back tonight. Have you any ideas what i'm a - doing wrong, b - what could be wrong..

Cheers in advance