"...cannot update one or more links..."

[almagg]

i have this formula:

=IF(ISNA(MATCH(C118&"*",'C:\Monthly Reports\Jul FY11\TFP EHS Report\[TFP noservice Event Details Report (All events) FY2011.xls]report'!$I$2:$I$400,0)),0,SUMIF('C:\Monthly Reports\Jul FY11\TFP EHS Report\[TFP noservice Event Details Report (All events) FY2011.xls]report'!$I$2:$I$400,C118&"*",$Z2:$Z400))

the 'MATCH' is to find out if the site is even in the list.
if it is it sums up all the matches in the Z column.

i keep getting the message "Excel is unable to update one or more links in this workbook..."
this is the only external link.
i am assuming it is referring to the [TFP noservice Event Details Report (All events) FY2011.xls]report'!

all the other internal links are ok.
any ideas?
thanks