Allow for user pressing cancel in File/Save API

I am using Access 2003 on Windows XP.

I am currently using the Windows File Open/Save Dialog box API to let a
user 
select where to save an excel file.  It works great, but I would like to 
inlcude code to allow for a user to cancel the save and return to the form

without anything happening.   I have tried a couple different things but 
can't get the desired actions to take place.  I copied the code from
mvps.org 
for the API and am using the following code in the application.

Private Sub cmdEx****t_Click()
    Dim strSaveFilename As String
    Dim strRptName As String
    Dim strFilter As String
       
    strQryName = "qryDynamicExcess"
        
    'Ask for SaveFileName
    strFilter = ahtAddFilterItem(strFilter, "Excel Files (*.xls)",
"*.xls")
    strSaveFilename = ahtCommonFileOpenSave( _
                                    OpenFile:=False, _
                                    Filter:=strFilter, _
                    Flags:=ahtOFN_OVERWRITEPROMPT Or ahtOFN_READONLY)
    
    strOutputFilename = strSaveFilename
    DoCmd.OpenForm "frmPleaseWait"
    DoCmd.TransferSpreadsheet acEx****t, , strQryName, strOutputFilename,
True
    
    Call FormatExcel
    'If Right(strRptOutputLocation, 1) <> "\" Then
    '   strRptOutputLocation = strRptOutputLocation + "\"
    'End If
    
    DoCmd.Close acForm, "frmPleaseWait"

Where would I put the code to allow for a cancel?

Thanks in advance for your help.