How to configure ACS HTTP Destination

I've configured an ACS HTTP Destination and ATO shows success but the recipient URL has not received any file.

My Config is as follows:

Name: MyName

API Name: MyName

Description: My Description

Protocol: HTTP

URL or Target Path: [ http:// ] myserver.com:port/mpl2/MPLAgileUpload.jsp within [..] is static.

Response Expected: No

Notification User: my agile user id

Request File Field: file

Filename Prefix: TO

File Number: 00000000073

check on enable user-defined Filename Extension

Filename Extension: axml

Additional Parameters: Null

On the first try I left the Response expected to 'Yes' but the ATO was at released status not copmpleted.  Once I changed Response expected to 'No', the ATO is at Completed.