Using a variable in a target path!

Hey Guys,
Ive got a function similar to the following:

function ping(btn_name) {

_root.btn_name.gotoandplay(2);

}

and im calling it:

ping(‘news’);

if i put a trace in the function I can see the the variable is being transfered correctly …but my news movie clips isnt play frame 2.

Ive made sure ive named the MC properly but im not sure if im ‘printing’ the variable out correctly into the target path.

Can anyone help?

Zaid