Marg
You have nothing to lose by trying, you will certainly need to explain what has happened in detail as Decision Makers prefer a claimants first statements on their limitations to any subsequent statements.
You don't say what the "mistake" was or whether you meet the criteria for the Going Out activity so I can't really offer any additional advice at the moment.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
