Using SendKeys

Hi EveryBody!
I am trying to automate the input of a printer form, however when I use Sendkey, it doesn't seem to work. My program automatically prints a word document out using a printer. The defaults of the printer are set to "Print to File." Thus, a little form pops up asking me to enter in the output file name. Is there anyway to automate the entry of an output file name? I tried using SendKey, however it is not working for me.

This is what I have:

Public Sub PrintDoc(sDoc As String)

Dim CurrentPrinter As Printer 'This must be declared.
Dim MyDoc As Object 'create a word variable
Set MyDoc = CreateObject("Word.Application")

With MyDoc

For Each CurrentPrinter In Printers
If CurrentPrinter.DeviceName = "apple" Then
Set Printer = CurrentPrinter
Exit For
End If
Next

.Documents.Open sDoc, , True

Printer.Print sDoc
SendKeys "test.prn, {ENTER}"

.ActiveDocument.Close 'Close The Document
.Quit
Set MyDoc = Nothing
End With

End Sub

I think I need to use the .SendKeys method, however I don't know what object to use for it. Thanks in advance for your help!