Yes, the ! may be disabled -- that's not the same as an error <s>. And it's not really a problem. Your dynamic additions to your base query are going to be filter conditions and stuff like that -- not your fields list.
I covered this in the walkthrough:
How do I get the the right information in my Datasets list
If you started this process with a non-dynamic query and you haven't changed your output fields list, you're already all set. If not, you can create a temporary query using literals, for example:
SELECT 10 AS OrderNo, 'Pending' As OrderStatus
... execute that query once in the Dataset window, press the little refresh button, and you should be all synched. If not, you can right-click in the Datasets window to explicitly Add fields [.. screen shot link here] by name.
In your case you can just use SELECT company as CNO from cono as your starting query. If the non-dynamic query works, then put = and quotes around it and it will work. Just because you can't always run it from that window doesn't mean it's broken.
The Designer tells you that there are no fields because you haven't set up your Datasets list. If you do a non-dynamic query first, run that and press the refresh button (see above) the fields will be in the Dataset properly. Or (see above) just add the fields to the dataset yourself. Once you've done that you "assign fields to a table (layout)", preview, etc.