Try this:
=IF(ISERROR(SUM('V:\DailyReports\Brasil\2006\[BRA-2006-01-31.xls]EquipDataCollation'!$D$5:$F$5)),"",SUM('V:\DailyRe ports\Brasil\2006\[BRA-2006-01-31.xls]EquipDataCollation'!$D$5:$F$5)).

When you hit enter, it will prompt you for the link. I hit escape, and it
seemed to work.

"DaveyC4S" wrote:

I have a set of formulae of the type below:

=SUM('V:\DailyReports\Brasil\2006\[BRA-2006-01-31.xls]EquipDataCollation'!$D$5:$F$5)

I am transferring the generation of quarterly reports to others and wish to
make it as easy as possible for them to update data. Therefore I would like
to generate formulae of the form above relating to files that do not yet
exist. The filename format is standardised.

What I can't seem to get Excel to do is ignore formulae where the file it
refers to does not exist yet.

Dave