One thing that probably isn't helping: DataTables should be working with ordered collections. Otherwise the table wouldn't consistently display the same rows in the same places. A related issue is that while I'm too lazy to RTFM, I don't think there's an iterator available for the HashMap interface. I think you have to get the keySet or valueSet and iterate on that.
The actual EL for retrieving a hashmap property (value) goes like this:
For retrieving a literal key's value:
An IDE is no substitute for an Intelligent Developer.