Is it error for the trial court to fail to determine the unlawfulness of withholding disability benefits for failure to file a disability report form?

Appellant contends it was error for the trial court to fail to determine the unlawfulness of withholding of disability benefits for failure of the beneficiary to file report forms. Appellant argues that there is no statutory requirement for the filing of the report forms, and the attempt to impose the reporting requirement is an impairment of the contractual right to said benefits as a part of the employment contract. Appellant cites Winslow v. City of Pasadena (1982) 130 Cal.App.3d 686, 181 Cal.Rptr. 873.