heidi sql grid editing error: column #4 not available

I get this error when I try to add a new row to Data table.

I created 2 tables before this one and it worked fine, but with this one I can't add data to the table.

Like this: I am placed in table e.x. "reservations". Then I head to Data tab and down there I do right click "Insert row". And then I got this error.