How to load data to devexpress combo,treeList in vb.net in

Question

I m using Devexpress form in vb.net but i cannot load data to devexpress combo from access database so can you help me to solve my problem..the problem is....

Dim myconn As OleDbConnection Dim dtt As New DataTable Dim constr As String = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=C:\PhoneDiary\MyDiary.mdb" Try myconn = New OleDbConnection(constr) myconn.Open() Catch

    End Try

    Dim sqlStr As String = "Select * from category;"
    Dim dAdapter As OleDbDataAdapter = New OleDbDataAdapter(sqlStr, constr)
    dAdapter.Fill(dtt)

     cmbCategory.DataSource = dtt........(Error Occurs)
    cmbCategory.DisplayMember = "CategoryDesc"
    cmbCategory.ValueMember = "CategoryID"

...........So Can you help me to solve this problem