In all our social media training courses we emphasise the importance of personalising your message and most of all explaining the reason why the connection should be made. Have a look at some my pending invitations that I looked at via the top level menu:
LinkedIn offers the latest three requests to your account.
Pending LinkedIn invitations
After clicking on the ‘Pending Invitations’ text these top three invitations are offered for review (below there is a more option so that you can look at all the rest of your pending invitations).
Clicking on the top right ‘message’ icon displays the personal message sent along with the justification.
Derek has amended the default message by adding my name, his name and giving a reason why we should be connected. On the other hand
This is the default message supplied by LinkedIn.
Who would you accept the invitation from (even if you knew the requestor)?