after converting Bitmap back to MemoryStream not saving proper image

[jaseem0712]

I have a data grid view,in update button i wrote code like this:

    Dim cid As Integer
            Dim dtid As Integer
            Dim cmpname As String
            Dim dtname As String
            Dim dtPhone As String
            Dim dtEmail As String
            Dim dtimage As Image
 
 
            For i As Integer = 0 To gv.RowCount - 2
                ' Dim rv = DirectCast(bSource.Current, DataRowView)
                Dim rv = DirectCast(gv.Rows(i).DataBoundItem, DataRowView)
                cid = rv.Row.Field(Of Integer)("Cid")
 
                dtid = rv.Row.Field(Of Integer)("dtId")
                cmpname = rv.Row.Field(Of String)("CompanyName")
                dtname = rv.Row.Field(Of String)("Department")
                dtPhone = rv.Row.Field(Of String)("Phone")
                dtEmail = rv.Row.Field(Of String)("Email")
 
                Using ms As New MemoryStream(rv.Row.Field(Of Byte())("empimage"))
                    dtimage = New Bitmap(ms)
                End Using
 
                adapter.UpdateCommand = New SqlCommand("UPDATE CompanyMaster_tbl SET CompanyName = @CompanyName", con.connect)
                adapter.UpdateCommand = New SqlCommand("update DepartmentMaster_tbl set dtName = @dtName,dtPhone = @dtPhone,dtEmail = @dtEmail,empimage=@dtimage  where dtId=@dtid", con.connect)
                adapter.UpdateCommand.Parameters.AddWithValue("@Cid", cid)
                adapter.UpdateCommand.Parameters.AddWithValue("@CompanyName", cmpname)
                adapter.UpdateCommand.Parameters.AddWithValue("@dtId", dtid)
                adapter.UpdateCommand.Parameters.AddWithValue("@dtName", dtname)
                adapter.UpdateCommand.Parameters.AddWithValue("@dtPhone", dtPhone)
                adapter.UpdateCommand.Parameters.AddWithValue("@dtEmail", dtEmail)
                adapter.UpdateCommand.Parameters.AddWithValue("@dtimage", dtimage)
                adapter.UpdateCommand.ExecuteNonQuery()
            Next

while executing i am getting error in this line :**adapter.UpdateCommand.ExecuteNonQuery()**
Error:`No mapping exists from object type System.Drawing.Bitmap to a known managed provider native type`
so i made small change in my code ..change is
instead of this line '**adapter.UpdateCommand.Parameters.AddWithValue(" @dtimage", dtimage)**' i added code like this

Dim md As New MemoryStream()
                dtimage.Save(md, System.Drawing.Imaging.ImageFormat.Gif)
                Dim imagedata As Byte() = md.ToArray()
     adapter.UpdateCommand.Parameters.AddWithValue("@dtimage", imagedata )

after adding this code am not getting any error..but not saving my image..that saving some another thing..what is wrong with my code