Work Item "Planned For" attribute Warning - Iteration Does Not Belong To Timeline
Accepted answer
The only way I was able to recreate something like this bug in 6.0.5 was in the Eclipse client (not in the Web client), and only when I was actively modifying the category mappings. In particular, it appears to be a caching problem ... if I shut down the Eclipse client and reopened it, the problem goes away.
3 other answers
"Iteration not associated to Team" - This occurs when you have multiple teams or (sub) team process areas in a RTC project and the team's timeline is unspecified.
Resolve by going to Manage This Project Area (gear icon). In the impacted Team Process Area or (sub)team process area; look for a relatively new setting called Timeline (just above where you add Members to a project). Adjust the drop down value to the Timeline associated to this team.
This Timeline is not the overall project area Timeline.