Opening and Closing Multiple Discs

I am working on a DVD burning robot. As part of the process, I need to open and close the DVD trays so that the robot can select the discs after burning. However, I ran into a problem. I can only control eject on one dvd recorder! Since I have two this is a problem. I've looked at this for an hour and can't figure out what happened. It can drive 1 dvd fine, but when I install it in another class, it doesn't work. Below is the class. I know I probably missed something simple, but for the life of me I can't figure it out.

Public Class openCloseDrive
'Api call to send the commands to the mci device
Private Declare Function mciSendString Lib "winmm.dll" Alias _
    "mciSendStringA" (ByVal lpstrCommand As String, ByVal _
        lpstrReturnString As String, ByVal uReturnLength As Integer, _
            ByVal hwndCallback As Integer) As Integer
'
'Api call to check for mci success or error
Private Declare Function mciGetErrorString Lib "winmm.dll" Alias _
    "mciGetErrorStringA" (ByVal dwError As Integer, ByVal lpstrBuffer _
        As String, ByVal uLength As Integer) As Integer

'will hold the mci return value
Dim retVal As Integer = Nothing

'This will contain the drive letter of the specified cd drive.
Dim _cdDrive As String = Nothing



Public Sub New(_driveLetter As String)
    _cdDrive = Chr(34) & _driveLetter & Chr(34)
End Sub

Public Function Open() As Integer
    'This will open the DVD Tray
    Dim retVal As Integer
    'This will Open the CD Drive Tray.
    mciSendString("open " & _cdDrive & " type cdaudio alias cd wait shareable", 0, 0, 0)
    retVal = mciSendString("set cd door open", 0, 0, 0)

    Return retVal
End Function

Public Function Close() As Integer
    'this Will close the DVD tray
    Dim retVal As Integer

    'This will Close the CD Drives Tray door.
    mciSendString("open " & _cdDrive & " type cdaudio alias cd wait shareable", 0, 0, 0)
    retVal = mciSendString("set cd door closed", 0, 0, 0)

    Return retVal
End Function


Public ReadOnly Property devices_InternalMCIStatus() As String
    '
    'Check the mci device to see if a error occured, and/or give 
    'some type of description even if everything was executed ok.
    '
    'Use this property if you want to, after each command you carried 
    'out to check and see if the command was successfully executed or 
    'not. It will tell you the status whether it was successful or not.
    '
    Get
        '
        'Make the length of this buffer 255 spaces since the returned
        'value could get pretty long, depending on what is going on.
        Dim buf As String = Space(255)

        mciGetErrorString(retVal, buf, 255)

        Return buf

        buf = Nothing

    End Get

End Property

      

        
        
        
      

    

End class