You will get as many answers to your questions as starts in the sky!
Just as they are not universal medications or universal treatements that help every kid, nor will every BIP be effective.
How good was the FBA, would be the first question. How many people who have seen a difficult child's behavior issues were in on writing the FBA, would be another question - as opposed to heresay.
In regards to the BIP, the implementation of a BIP wouldn't cause it's failure - either the incorrect implementation, not following it at all, or a difficult child who has moved on to a different set of behaviors could all be factors. Additionally, were any members of the team writing the BIP ever wittnesses to successful redirection of said difficult child? Are the things listed in the BIP just "form" or are they real tried and true methods that have be susscessful in the past with this particular difficult child?
In order to write a successful FBA and ultimately a successful BIP, there has to be a clear understanding of the issues facing said difficult child. Sometimes identifying the function of a problem is very tricky and take several wacks before clear understanding dawns.
In my difficult children case I was extremely, extremely fortunate to have a group of caring educated professional and lay team members who understood the importance of the task and had both years of experience and an honest interest in my son's well being.
When it works, it usually works well. When it doesn't, it is usually dismal - but the reasons are rarely cut and dry across the board.
Sharon