DateDiff function???????

I have a temp table that gives me two time entries we'll say invoice_date1 and invoice_date2

i need to extract the time difference between the two dates and if it is greater than an hour or 60 minutes i need to return it in a count statement.

how would i do this?

i did this and it is not working:
SELECT COUNT (*)
FROM #WorkingData
WHERE ledger_id IS NULL
AND ledger_id < 0
AND DATEDIFF ( mi , invoice_date1, invoice_date2) > 60

the only part that does not work in this is my date statment when i query before that statement I get correct results after that statement I do not.

Try to put the , mi in a string ,DATEDIFF ( "mi" , invoice_date1, invoice_date2) > 60

Yes, that works great for a static date!!!