Class Balance Totals Do Not Match Bank Balance Total

Hello!  I am trying to understand why my Class Balance Totals do not match my overall Bank Account Total.  We are a church with 1 bank account and all funds are tracked through 7 different classes (both income and expenses).  It would seem to me that the 7 individual class balances should add up and equal the total of our bank account.  There are no transactions shown as unclassified.  In addition to the two balances not ever matching, I am also trying to figure out why there is a fluctuation between these totals - it isn't always off by the same amount.  It appears that Payroll Liabilities have some effect, but I can't quite pinpoint how these are reflected either.  The Liabilities are tied to our General Fund class, but even if I zero them out, the two balances still don't match.   Thanks for the help!