checkbox subitem events

Hello community,
I have a subitem type checkbox and i would like to save the selected property in my form so i set the OnEvent of the OnChange procedure of the TypeOptions of my item.
At runtime i get the exception 'Ajax event "TypeOptions.Events.OnChange" not found!' when i click on the checkbox and it didnt trigger the breakpoint inside.
Any idea why ?
Regards
I have a subitem type checkbox and i would like to save the selected property in my form so i set the OnEvent of the OnChange procedure of the TypeOptions of my item.
At runtime i get the exception 'Ajax event "TypeOptions.Events.OnChange" not found!' when i click on the checkbox and it didnt trigger the breakpoint inside.
Any idea why ?
Regards