You need to share the jobs, not always be the boss of the co-op jobs. It seems that farmville gives everybody a fair chance. You can keep being the boss of jobs and than eventually you will need to find new neighbors to do co-op jobs with.
How do I know this? A friend of mine was always wanting to do co-op jobs but never wanted to be the helper. After doing two jobs with him as the helper it seemed that this error kept happening. When I would go into the co-op job list his job also did not show up on my end. Anybody who never did a job with him before of course could join, although eventually, they also received the same error
