What I understand from the context is that if a dispute arises between the parties, then they will try to settle this dispute through a mediator. If the mediation is unsuccessful, then the mediator will issue an "acta de imposibilidad de mediación" i.e. a report stating that the mediation was unsuccessful. See an example in context below:

"The CCB Dispute Resolution
Once the CCB accepts jurisdiction over a complaint (typically within 10 business days of filing), DRS schedules an on-site mediation between the owner and contractor, giving each party at least 14 days’ notice of the date. Either party may bring an attorney to this mediation, or include subcontractors or other consultants. If the mediation is successful, the mediator will issue a binding settlement agreement to be signed by each party. If the mediation fails, the mediator will issue a mediation report that may be used by either party in subsequent court proceedings. Depending on the complexity of the Complaint, issuance of a mediator report can take anywhere from 10 days to two months."
http://www.pmblaw.com/residential-construction-defect/