I am new to trial balances and I can't get my problem to balance. I think that I have some of the items incorrectly categorized (debit/credit). Here's what I have...

Cash and cash equivalents (debit)
Accounts receivable (debit)
Prepaid expense (short term) (debit)
Inventory (debit)
Delivery equipment (debit)
Accum depreciation - delivery equipment (credit)
Store fixtures (debit)
Accum depreciation - store fixtures (credit)
Investment in securities (long term)??
Accounts payable (credit)
Accounts payable, long term (credit)
Notes payable, short term (credit)
Paid in capital (credit)
Common stock (credit)
Retained earnings (debit)
Dividends, distributed 12/12/07 (debit)
Net sales revenue (debit)
Cost of sales (debit)
General and administrative expenses (debit)
Selling expense (debit)
Interest expense (debit)
Interest income (debit)
Income tax expense (debit)

I know that I've gone wrong somewhere w/ my categories... but don't know where. Can someone help, please?

Try to balance using a clear understanding of simple banking terms-
Credits are funds going into an account, i.e. a deposit
Debits are funds coming out of an account, i.e. a withdrawal.
It looks as if 75% of your list is mislabled as credit or debit, i.e. how would interest income be a debit?