Hi Daniel,
Are you serving your page though a web server (http)? Or are you just double-clicking your html file and running locally (without a web server)?
Daniel:
Why do you add http://ho213-radell19:6080/arcgis/rest/services/dtcook13/Final/MapServer as a dynamicMapServiceLayer and then give it imageParameters before adding it to the map?
Can you explain how that answered your question?