formula not reading when an employee shift changes

I need a formula that will be able to show what shift someone is on if the shift changes, for example. if one of my employess shift changes from and 8hr to a 10 hr on january 16th 2014 then I would like the raw sheet to show the old shift, the new shift and when the new shift started (date). the index formula I have will only show one shift even if there are new dates with a different shift. the formula pulls from teh sheet name editor.

i really want the shifts to be fifferent if it was change on a certain date then from that date the employee shift will reflect new shift but still keep the previous shift prior to the day the new shift started.

I've attached a sample workbokk to show.

I would like a formula that will show an agents shift for a particular day... for example and agent work 8hrs during the week however if I change the agent's shift a day during the week (wednesday) to 10 hrs then the formula should show that the agent worked 10hrs on wednesday. basically I need shifts to match agents name and date.