Converting String to Btye[]

I having problem with my code.

i'm developing a login page with fingerprint scanner. Inserting the template of fingerprint scanner to sql database works fine (nvchar(MAX)),

but when selecting the template from sql im getting error like this: Unable to cast object of type 'System.String' to type 'System.Byte[]'.

here's my code:

Dim cn As New SqlConnection(ConnectString())
          cn.Open()
          dim bytes as Byte()
          sqlCommand.CommandText = "Select template from usertbl where username='" + registration.txtusername.Text + "'"
          sqlCommand.CommandType = CommandType.Text
          sqlCommand.Connection = cn

          Dim lrd As SqlDataReader = sqlCommand.ExecuteReader()
          Dim usr
          While lrd.Read()
              usr = lrd("template")

          End While


          bytes = Nothing
          bytes = usr

              template = New DPFP.Template()
              template.DeSerialize(usr)
              'Perform  match
              matcher.Verify(FeatureSet, template, matchResult)
              If matchResult.Verified Then
                  EventHandlerStatus = Gui.EventHandlerStatus.Success
              MsgBox("Verified!")
              Me.Hide()
              registration.Show()
              Else

              EventHandlerStatus = Gui.EventHandlerStatus.Failure
              MsgBox("Please Try Again!")
              End If

I'm using DigitalPersona 4500 BTW

Tags: String