Electric boot on Vauxhall Vectra sticking on closing?

I wonder if you could help me as I have a Vauxhall Vectra Estate with a 56 registration and as the boot is trying to close, it jams. I can push it down and it locks but it will not close as it should electrically. I have attempted to put WD40 onto the struts but so far no joy. Any suggestion would be appreciated. Thank You.