Movie Clip Button Tutorial problem

programming flash
1

Hello all !
I am folloing the tutorial movie Clip Buttonn wich is on kirupa.
I follow it step by step but i am having problem with it :confused:

When i have to put my code wich is
This.button_mc.onRollover <----------- i cant select it by just typing it in the list, i have to manually select it or right it completly, and i think the problem is here.
then i finish my code. wich is :

this.button_mc.onRollOver = fonction () {
button_mc.gotoAndPlay("_over");
}

then i launch and i get this error message :

Error Scene=Scene 1, layer=actions, frame=1:Line 1: Syntax error.
this.button_mc.onRollOver = fonction () {
Total ActionScript Errors: 1 Reported Errors: 1

i really dont understand because i follow the tutorial step by step…
plz help me !
thx you !
bye.