UPDATE not working???

Beginner question this one (me being a designer and all) but it has been doing my head in for a few hours now so I thought I would put it to the group. I am trying to create a very simple database to keep track of my business expenses - and all to further learn PHP - but am stuck. The following update doe snot work and I have no idea why. If I change it to an INSERT it works (ie creates a new entry) but the update is working. Any ideas on where I should be looking for the problem?? $sqlQuery = "UPDATE $db_table SET Date = '$date', Company = '$company', Description = '$description', Amount = '$amount', PaidBy='$paidBy', ReImburse='$reImburse', ReIMburseDate='reImburseDate', Note = '$note' WHERE id='$id'"; Thanx in advance James