A lien given by this chapter is not affected by any inaccuracy in the particulars of the lien, but, as against all persons except the owner of the property, the lien claimant must be    concluded by the dates therein given, showing the first and last items of the claimant’s account. A lien may not exist for a greater amount than the sum claimed in the lien, nor for any amount, if it be made to appear that the claimant has knowingly demanded more than is justly due.