Kernrechtsfrage
Whether the minimum contribution period of one year for invalidity insurance benefits was met.
Extrahierter Entscheid
The insured did not prove that contributions had been deducted for more than eleven months; the minimum contribution period was not established.
Extrahierte Begründung
The cantonal court was entitled to refuse further witness hearings because the available evidence, including the former employer's statements and the prior remittal instructions, did not show that the requested witnesses could establish the required proof with sufficient certainty.