I was able to get it working for one reportlet, but not the others. I checked the API call, and seems that is what is failing. The API calls bookmarks.GetReportDescription with the reportlet ID and the error is returned.
Looks like either the issue is with the API function, or the ID being referenced is incorrect.
Report builder and dashboards are 2 separate tools completely independent of each other. They cannot be shared across each other in essence.
If you have a dashboard with multiple re-portlets in it. You will then have to re create it using the report builder interface. You may even find in a few rare instances one cannot be reproduced easily in the other.