Unenforceable wage claim due to failure to substantiate contractual entitlement

The Federal Labor Court (BAG) reversed the appellate court's judgment and dismissed the plaintiff's appeal, thereby upholding the labor court's initial ruling in favor of the defendant and ordering the plaintiff to bear all costs of the proceedings. The dispute concerned a claim for unpaid wages, where the plaintiff sought to enforce a wage agreement or contractual remuneration terms against the employer. The decisive legal basis centered on the interpretation and validity of the individual labor contract provisions governing compensation, with the court determining that the plaintiff failed to substantiate the claimed wage entitlement or that the contractual terms did not support the higher amount sought, resulting in a judgment against the employee.