Posted: 29/04/2014 at 19:46
Grass seed needs warm temperatures and light in order to germinate - I'm afraid it may have been too cold when you sowed the seeds, and putting soil on top will have kept the light away
I'm going to say, wait until the cold snap forecast for the the weekend is over and when night time temperatures are averaging around 10C, then sow the seed again, water it and leave it - as Artjak says, do something to keep the birds off - canes with DVDs hanging on strings or something similar maybe. In warmer weather and with no soil on top the seed should germinate within 10 days.
More info here http://www.rhs.org.uk/advice/profile?pid=424