A waiver by Company of a breach of any provision of this Agreement by the Executive shall not operate or be construed as a waiver or estoppel of any subsequent breach by the Executive. No waiver shall be valid unless in writing and signed by an authorized officer of Company. A waiver by the Executive of a breach of any provision of this Agreement by Company shall not operate or be construed as a waiver or estoppel of any subsequent breach by Company. No waiver shall be valid unless in writing and signed by the Executive.