Try to give joins again in both Physical and BMM Layer and clear the cache once again. Since, it is the old instance and you are migrated from 10g to 11g, the server might not recognize the joins properly...
Thanks for the suggestion Chaitanya,
One point here is, we have not migrated the instance to 11g as of now. And these joins are given recently only.
It may be due to Logical Table Source Levels set up incorrectly like other 100 reasons... but is hard to tell with almost 0 informations