How to send DateTime parameters to WCF DataService

I have simple function on the DataService that get DateTime parameter

[WebGet]
public IQueryable<Job> LoadJobsByDate(DateTime startDate, DateTime endDate)
{
    var context = this.CurrentDataSource;

    var jobs = from j in context.Jobs
               where j.CreatedDate >= startDate && j.CreatedDate <= endDate
               select j;

    return jobs;
}

What ever syntax I'm try to send I get error.

I tried

var query1 = newContext.CreateQuery<Job>("LoadJobsByDate")
             .AddQueryOption("startDate", 
                 string.Format ("'{0:yyyy-MM-ddTHH:mm:ss}'", DateTime.Now));  

or:

var query1 = newContext.CreateQuery<Job>("LoadJobsByDate")
             .AddQueryOption("startDate", 
                 string.Format ("'datetime{0:yyyy-MM-ddTHH:mm:ss}'", DateTime.Now));  

Please advice