I have a conditonal sum that currently works fine as follows;

{=SUM(IF(Sheet1!$I$3:$I$5000="ProductType",IF(Shee t1!$K$3:$K$5000="T0",
IF(Sheet1!$O$3:$O$50001,Sheet1!$F$3:$F$5000,0),0) ,0))}

What I am now trying to do is to add another argument to filter the years
which are in column A in general format, something like;
IF(Sheet1!$A$3:$A$5000="2005",,)

When I use the Conditional sum wizard it works when I enter any combination
of two arguments, but when I try using all three I get the error;

"Run Time error '1004' Unable to set the ForulaArray property of the Range
class"

Can anybody help me to solve this, or can you only use two arguments with
the Conditional Sum wizard?

thanks, Les.