Problems with S.I. Switch on 2010 Fender American Deluxe Strat (Neck Pickup)

[tonystark]

Hi, I'm having the problem mentioned above: When the SI switch is ON, the neck pickup suddenly goes very soft, i.e. softer than whatever the volume was when the switch was OFF. Would anyone happen to know why or how to solve the problem? Is this normal?

Thank you!