Having problems with a custom query report

I am trying to create a custom query report so that on a daily/weekly and monthly basis every technician and the manager get the report to see what work they have achieved on that day/week/month.

I want to include calls that they have closed in that timeframe and also calls that they have just made notes on and logged a work log against every request.

I currently have this code below but it doesn't seem to work;

SELECT ti.FIRST_NAME 'Technician',wo.WORKORDERID 'Request ID',wo.COMPLETEDTIME 'Completed Time' FROM WorkOrder_Threaded wot INNER JOIN WorkOrder wo ON wot.WORKORDERID=wo.WORKORDERID LEFT JOIN WorkOrderStates wos ON wo.WORKORDERID=wos.WORKORDERID LEFT JOIN LevelDefinition lvd ON wos.LEVELID=lvd.LEVELID LEFT JOIN StatusDefinition std ON wos.STATUSID=std.STATUSID WHERE ((( std.STATUSNAME = 'Closed') AND ((wo.COMPLETEDTIME >= <from_thisweek>) AND ((wo.COMPLETEDTIME != 0) AND (wo.COMPLETEDTIME IS NOT NULL)))) AND ((wo.COMPLETEDTIME <= <to_thisweek>) AND ((wo.COMPLETEDTIME != 0) AND (wo.COMPLETEDTIME IS NOT NULL)))) AND wot.THD_WOID=wot.WORKORDERID ORDER BY 3

I get this fault below;

Base table or view not found, message from server: "Unknown table 'ti' in field list"

Can you help on this?