Action in the first contribution of a user (Rules and trigger module)

Hello,

I try to define a rule / action during the first contribution (the first node created) of a user recently registered (the action what I want is to send an email of validation of the new user account and its first contribution).

For it I found the Rules module which allows to create rules very personalized on triggers (triggers rules).

I created thus one and I defines firstly the event " saving after-party has new tell ".

The big mistake, it is when I add a condition " Rules-> Check has truth been worth " to make a boolean which is going to allow me to say if it is the first contents of the user or not (and thus if it is the first one, an email is sent to the administrator who will validate the new user account and its first contribution). And that, I really don't know how to do!!!

Obviously nothing says to me that I made a mistake in my approach or while I make a mistake about module...

If somebody was already confronted with this problem or know an other method...please help me !!

thx