ho provato in questo modo....
Dim DataSource As String, stringasql As String
Dim conn As New Data.SqlServerCe.SqlCeConnection
Dim adp As New Data.SqlServerCe.SqlCeDataAdapter
Dim ds As New Data.DataSet()

DataSource = "Dati.sdf;Encrypt Database=True;Password=xxxx;File Mode=shared read;Persist Security Info=False;"

conn.ConnectionString = DataSource
conn.Open()

stringasql = "SELECT idlog,login FROM login"
adp.Fill(ds)
conn.Close()



Me.CbLoin.DataSource = ds.Tables("Login")
Me.CbLoin.DisplayMember = ds.Tables("Login").Columns(1).ColumnName
Me.CbLoin.ValueMember = ds.Tables("Login").Columns(0).ColumnName