linked cells will not update unless source file is open

Can anyone help me figure out why my workbook will not update unless the source file is open? I have no macros just formulas to index/match etc from the source file (Production Schedule, Plant schedule tab). Both files were 2003-07 format and converted to 2010. This file will be a major reference for other users including my boss and I dont want anyone viewing this file to have to open a source file from another directory. Both files are located within the same server drive, but within different folders. Here is the only formula that refers to the source if this helps:

When source file is open: =LOOKUP(9.9999E+307,CHOOSE({1,2},0,SUMPRODUCT(('[Production Schedule.xlsx]Plant Schedule'!$D$4:$D$220&'[Production Schedule.xlsx]Plant Schedule'!$E$4:$E$220=$C9)*(INDEX('[Production Schedule.xlsx]Plant Schedule'!$N$4:$LM$220,1,MATCH(BQ5,'[Production Schedule.xlsx]Plant Schedule'!$N$1:$LM$1,0)):INDEX('[Production Schedule.xlsx]Plant Schedule'!$N$4:$LM$220,ROWS('[Production Schedule.xlsx]Plant Schedule'!$N$4:$LM$220),MATCH(BQ5,'[Production Schedule.xlsx]Plant Schedule'!$N$1:$LM$1,0)+23)<>""))*INDEX('[Production Schedule.xlsx]Plant Schedule'!$J$4:$J$220,MATCH(TRUE,INDEX('[Production Schedule.xlsx]Plant Schedule'!$D$4:$D$220&'[Production Schedule.xlsx]Plant Schedule'!$E$4:$E$220=$C9,0),0))))

When source file is closed: =LOOKUP(9.9999E+307,CHOOSE({1,2},0,SUMPRODUCT(('S:\Logistics\Production Schedules\[Production Schedule.xlsx]Plant Schedule'!$D$4:$D$220&'S:\Logistics\Production Schedules\[Production Schedule.xlsx]Plant Schedule'!$E$4:$E$220=$C9)*(INDEX('S:\Logistics\Production Schedules\[Production Schedule.xlsx]Plant Schedule'!$N$4:$LM$220,1,MATCH(BQ5,'S:\Logistics\Production Schedules\[Production Schedule.xlsx]Plant Schedule'!$N$1:$LM$1,0)):INDEX('S:\Logistics\Production Schedules\[Production Schedule.xlsx]Plant Schedule'!$N$4:$LM$220,ROWS('S:\Logistics\Production Schedules\[Production Schedule.xlsx]Plant Schedule'!$N$4:$LM$220),MATCH(BQ5,'S:\Logistics\Production Schedules\[Production Schedule.xlsx]Plant Schedule'!$N$1:$LM$1,0)+23)<>""))*INDEX('S:\Logistics\Production Schedules\[Production Schedule.xlsx]Plant Schedule'!$J$4:$J$220,MATCH(TRUE,INDEX('S:\Logistics\Production Schedules\[Production Schedule.xlsx]Plant Schedule'!$D$4:$D$220&'S:\Logistics\Production Schedules\[Production Schedule.xlsx]Plant Schedule'!$E$4:$E$220=$C9,0),0))))