How many bars does the battery indicator on the HR92 report ? If it's less than a full three bars with new batteries try increasing the tension on the battery contacts in the bottom of the compartment. This can be done from underneath with the HR92 removed by bending the contacts up slightly with a tiny screw driver.
Also, are you fitting Alakalines or some other kind ? If you're not using Alkalines make sure you have the battery type setting in the menu correct.