Unless the employer shall have actual knowledge of the occurrence of the injury, or unless the employee, or some one on his behalf, or some of the dependents, or some one on their behalf, shall give notice thereof to the employer within fourteen days of the occurrence of the injury, then no compensation shall be due until such notice is given or knowledge obtained. If the notice is given, or the knowledge obtained within thirty days from the occurrence of the injury, no want, failure, or inaccuracy of a notice shall be a bar to obtaining compensation, unless the employer shall show that he was prejudiced by such want, defect or inaccuracy, and then only to the extent of such prejudice. If the notice is given, or the knowledge obtained within ninety days, and if the employee, or other beneficiary, shall show that his failure to give prior notice was due to his mistake, inadvertence, ignorance of fact or law, or inability, or to the fraud, misrepresentation or deceit of another person, or to any other reasonable cause or excuse, then compensation may be allowed, unless, and then to the extent only that the employer shall show that he was prejudiced by failure to receive such notice. Unless knowledge be obtained, or notice given, within ninety days after the occurrence of the injury, no compensation shall be allowed.