This is what I'm trying to do.....
Col E Col H
9/17/08 in
9/18/08 ti
9/19/08 ot
When H13:H36 = in OR H13:H36 = ti, Then return the average date from
E13:E36 (when there is an average date but blank when cells in Col H & E are
blank.)

I have been using the following which works fine but now it needs to return
the result when H="in" or H="ti". (2 conditions not just 1)
=IF(ISERROR(SUMIF(F12:F45,"IN",C12:C45)/COUNTIF(F12:F45,"IN")),"",SUMIF(F12:F45,"IN",C12:C 45)/COUNTIF(F12:F45,"IN"))