how to send an email based on selected checkbox

how to send an email based on selected checkbox

I posted this once already, but the post disappeared, so I'm not sure what I did wrong.

Anyway....

I have a checkbox called "ready to be invoiced."  I want to have an email sent to myself when the girl who is doing the input selects that checkbox.

In other words, I want the checkbox selection to be set to "true."

Right now, I have the script set up and it works perfectly, EXCEPT it sends an email any time there is any activity regarding the checkbox -- i.e., whether it's clicked on to select it, then clicked on to de-select it (if selected in error), etc.

Here is the script as it stands:

if (input.Ready_To_Be_Invoiced)
{
}
sendmail
(
    To       :  "email@email.com" 
    From     :  zoho.adminuserid 
    Subject  :  "Restaurant ready to be invoiced" 
    Message  :  input.Restaurant + " is ready to be invoiced -- go check it out!" 


Thanks in advance --
Julia