count condition in RDLC

Class TItem
    Public Property Sex As Integer
    Public Property Grade As Integer
    Public Property studentID As Long
End Class

Sub Main()

    Dim Items = { _
        New TItem With {.Sex = 1, .Grade = 1}, _
        New TItem With {.Sex = 1, .Grade = 1}, _
        New TItem With {.Sex = 0, .Grade = 1}, _
        New TItem With {.Sex = 0, .Grade = 1} _
    }

    Dim ItemsList As New List(Of TItem)(Items)

    Dim n = Aggregate Item As TItem In ItemsList Where Item.Sex = 1 And Item.Grade = 1 Into Count()

    MsgBox(n)
End Sub

SELECT Sum(id) 
FROM Table
WHERE sex = 1 AND grade =1 ;

sum(iif(Fields!Sex.Value = 1 and Fields!grade.Value = 1, 1,0))