Open and close a CD DRIVE in visual basics 2005 express?

I used the following code to open and close the cd drive

Private Declare Function mciSendString Lib "winmm.dll" Alias "mciSendStringA" (ByVal lpstrCommand As String, ByVal lpstrReturnString As String, ByVal uReturnLength As Long, ByVal hwndCallback As Long) As Long

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim lRet As Long

lRet = mciSendString("set CDAudio door open", vbNullString, 0, 0)

End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)HandlesButton2.Click

Dim lRet As Long

lRet = mciSendString("set CDAudio door closed", vbNullString, 0, 0)

End Sub

and it does open and close it but instantly after it opens the program comes across this error

A call to PInvoke function 'Open And Close!WindowsApplication1.Form1::mciSendString' has unbalanced the stack. This is likely because the managed PInvoke signature does not match the unmanaged target signature. Check that the calling convention and parameters of the PInvoke signature match the target unmanaged signature.

Can anyone help me with this Ive done forum searching on atleast five other sites but they all just give me examples of the same code that continues to give this error.