Error when adding new line with custom Checkbox

Hello,

the Error I get is:

Error processing Multi Row Update process.
ORA-01403: no data found

At first how my site looks like:
I have a Tabular Form, showing columns: ID, NAME, CHECKBOX (!value! from DB just for testing), Checkbox Check (this is the real Checkbox).
I created my Checkbox with the help of this site: http://www.inside-oracle-apex.com/checkboxes-in-tabular-forms-the-easy-way/ (really easy way, works just fine)

But my Problem is, I couldn't insert a new row, with my custom Checkbox = checked. When i do, i get the error from the top. All other possible changes work (change existing values, delete rows, insert new row with Checkbox = unchecked..)