EF how to filter data by date

I' using EF 4, I have a property DateTimeStart in my entities with datein this format 16/08/2012 08:14:40, I would like query with EF and find all the entities within the date 16/08/2012 only. Using this code below code I receive this error

The specified type member 'Date' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.

my code

 DateTime dateTimeNow = DateTime.UtcNow;
        DateTime dateNow = dateTimeNow.Date;
        return db.EventCustoms.Where(x => x.DataTimeStart.Date <= dateNow)
            .Select(y => new { y.EventId, y.EventTitle, y.DataTimeStart });