Need help uploading an image to AWS S3 using REST PutObject

Hello,

I am trying to upload an image to Amazon Web Services S3 bucket using the REST PutObject request. I am using an expiring signature.

I'm using the PutObject REST request in SoapUI Pro with these parameters:
Expires
AWSAccessKeyId
Signature
Key

The Media Type is set to image/jpeg

A jpeg image is added as an attachment

When I submit this request I get the following error back: Marlformed XML: The XML you provided was not well-formed or did not validate against our published schema.

Does anyone have experience with this and can help?

Thanks!