Verify that both the Sensor Bar and the Wii Remote's pointer lens are free of obstructions and contamination (stickers, heavy smudges, etc.). The pointer lens is the tinted rectangle at the end of the Wii Remote. If the Wii Remote Jacket is being used, verify that it's securely in place on the Wii Remote. If the Wii Remote Jacket is askew; it might be partially blocking the infra-red sensor on the front of the Wii Remote.
Check the sensitivity the Wii Remote is set to. This can be adjusted in The Wii Settings on the Sensor Bar menu under the Sensitivity options. It can be adjusted with the + and - buttons of the Wii Remote.