new leads wont go on to spark plugs

[juddye30]

hi there, im recently having a little trouble with some of my leads so i decided to change them. I found a genuine set on ebay not very old and thought they would do for the time being. However the lead wont go over the plug???? im capable at doing abit but cant help that im having a blonde moment can anyone shed some light on this please????

[Brianmoooore]

Unscrew the caps on the plug terminals?