§ 121. Notice of lien. Such notice may be filed at any time after the completion of the work, but must be filed within one year after the agreed price for furnishing or placing such monument, gravestone, inclosure or other structure becomes due, and shall state that the lienor has a lien on such monument, gravestone, inclosure or structure for the purchase price thereof, or some unpaid part of such purchase price, with interest, specifying the amount agreed to be paid, and the amount unpaid, with a description of such monument, gravestone, inclosure or other structure, and the location of the plot upon which it stands, and the names of the persons with whom the agreement for the purchase and erection of the structure, or for the performance of such labor was made. The notice shall be signed and verified by the lienor. The lienor shall, within ten days after the filing of such notice, serve a copy personally, or by mail, upon the person with whom the agreement for the purchase and erection of such monument, gravestone, or other structure, or for the performance of labor thereon was made, and upon the owner of the lot upon which such monument, gravestone or other structure is erected, if the name and residence of such owner can, with reasonable diligence be ascertained.