用linq查找某一天的数据?

db.mytable.Where(t => t.uid == uid && System.Data.Linq.SqlClient.SqlMethods.DateDiffDay(t.dateadd, dateadd) == 0).FirstOrDefault();

报错:LINQ to Entities 不识别方法“System.Nullable`1[System.Int32] 

我不知这样写对不对,还是有其它方法?

------解决方案--------------------
LINQ to Entities 可以使用SqlFunctions.DateDiff

db.mytable.FirstOrDefault(t => t.uid == uid && 
System.Data.Objects.SqlClient.SqlFunctions.DateDiff("day", t.dateadd,dateadd)==0;