Unless the employer has actual knowledge of the occurrence of the injury or unless the injured worker, or a dependent or someone in behalf of either, gives written notice thereof to the employer within 14 days after the occurrence of the injury, then no compensation shall be due until the notice is given or knowledge obtained. If the notice is given or the knowledge obtained within 30 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 shows prejudice by such want, defect, or inaccuracy, and then only to the extent of the prejudice. If the notice is given or the knowledge obtained within 180 days, and if the employee or other beneficiary shows that failure to give prior notice was due to the employee’s or beneficiary’s mistake, inadvertence, ignorance of fact or law, or inability, or to the fraud, misrepresentation, or deceit of the employer or agent, then compensation may be allowed, unless the employer shows prejudice by failure to receive the notice, in which case the amount of compensation shall be reduced by a sum which fairly represents the prejudice shown. Unless knowledge is obtained or written notice given within 180 days after the occurrence of the injury no compensation shall be allowed, except that an employee who is unable, because of mental or physical incapacity, to give notice to the employer within 180 days from the injury shall give the prescribed notice within 180 days from the time the incapacity ceases.