Problem reconciling my account

[Ruth Morley]

I have been reconciling a foreign bank account that I had neglected. A
couple of months went fine but when I got to the third one I erroneously
entered my closing balance (on the first reconcile screen) as a positive
when in fact it should have been negative, So instead of putting -200 euros
(minus) I enter 200 euros, Obviously when I finished the reconcile I was
400 euros off. I quickly detected my error but have not found a way to
change the original entry.
I tried pausing the reconcile and then when it showed me the first screen
again - I tried changing it but no luck.
Any ideas?