If your source monthly sheets are like so:
CustName = Column C
Sales = Column D

In Summ,
just replace the formula in B2 with:
=IF(COUNTA($A2,B$1)<2,"",SUMIF(INDIRECT("'"&B$1&"' !C:C"),$A2,INDIRECT("'"&B$1&"'!D:D")))
then copy B2 across/fill down to populate the summary table
That should do it for you.

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This part of the earlier formula which points to the CustName in col B:
INDIRECT("'"&B$1&"'!B:B")
we change: B:B to C:C (the new col for the CustName)

and this part which earlier points to the Sales in col C:
INDIRECT("'"&B$1&"'!C:C")
we change: C:C to D:D (the new col for the Sales)
--
Max
Singapore
http://savefile.com/projects/236895
xdemechanik
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"John Luc" wrote in message
...
Hi Max
Please can I ask you another favour can you alter formula for me to
reflect the following please
CustName = Column C
Sales = Column D

Tried to this myself and failed.
Regards
John