in the said proviso is 'shall'. It is mandatory. However, Section 35 makes it clear, that where an instrument has been admitted in evidence without there being objection at the time of admitting the said instrument in evidence, then such admission shall not, except as provided in Section 58, be called in question at any stage of the same suit or proceeding on the ground that the instrument has not been duly stamped. Section 58 deals with the power of the Appellate Court to review the finding recorded by the original Court under Section 34 of the Act, either suo motu or on the application of the Deputy Commissioner. Section 36 of the Act deals with admission of improperly stamped instrument. The State Government may make rules providing that, where an instrument bears a stamp of sufficient amount but of improper description, it may, on payment of the duty with which the same is chargeable, be certified to be duly stamped, and any instrument so certified shall then be deemed to have been duly stamped as from the date of its execution."