Error in Firefox: TypeError and unreachable code after return statement

Code Examples Form
#1

Hello,
using a Master/Detail form, i get in firefox an error: TypeError: b is null jquery.js:3:19123
and then some warnings unreachable code after return statement
IE, Chrome and Opera works fine

The error comes up when the Detail form runs this javascript:

function sc_form_onload()
{
do_ajax_form_arten_lk_10_add_new_line();
}

Thanks for any help!

Siggi