Unfortunately, it is often difficult to determine the root cause through email as there are many reasons why this may happen. The material covering the wall may affect the tool's accuracy. For example, if there is metal in the paint or wallpaper, it may not be able to distinguish the stud from the outer wall covering. Fresh paint often needs time to cure due to metallic substances used in the manufacturing process. Heavy metal plumbing or electrical will also have the same effect. Please also check to ensure your battery is not low and that the unit was not dropped or harmed in some way.
If you still cannot determine the cause of the malfunction, please return the tool to us for repair or replacement. Please send it to:
STANLEY TOOLS QA
1000 Stanley Drive, Concord, NC 28027.
Be sure to include your name and return address in the package.