Opening Balance brought forward is wrong!

I am currently using a trail before I sign up long term and am having problems getting the balance on Free Agent to match up with bank statement! I have entered all credits and debits correctly and the additions and subtractions are correct but it looks like the 'balance brought forward' on the Bank Accounts page is wrong! Strangely enough, the difference between the Free Agent balance and my actual Bank Statement balance is the same as the first credit I entered, yet I have entered this invoice as paid!

The only thing I can think of is that when I first started to enter all my details the other day, I entered my correct opening balance and also entered a client who had an overdue invoice of the same amount of the deficit, as this showed up on the Home page as being 'red' - but I have changed this to 'paid' status!!! HEELLLLLPP!!!!!

Any ideas would be greatly appreciated to a new comer to this great package!

Thanks, Les.