Trouble installing humbucker covers

[guitaromatic]

Can somebody help me?? I have a flying v faded and want to cover the pickups. So i bought the correct covers, installed the first one (52mm) on to the bridge pick up - no problem ( I am using the electrical tape method rather than dipping and waxing). The second one - not so good! When I put the cover on the pick up it cuts out. Take the cover off and it works just fine. Why is it doing this?? Any ideas? Help would be most appreciated. Thanks