Zero values adding to the total

In webi report iam getting null values instead of that i place it as a 0.

after i have to add 3 columns for me getting data is.

col1   col2  col3  total( col1+col2+col3)

252     0       0     25200  value is 252 for me getting 25200 two 0s are added and displayed in total column.

for null values i put formulae as

=If(IsNull(Sum([ABS Collection].[Collection] Where ([ABS Collection].[Customer Code] InList("COPART0032";"COPART0033";"COPART0034") And ([ABS Collection].[Crop Group]

InList("Cotton";"Field Crops";"Vegetables")))));"0"; Sum([ABS Collection].[Collection] Where ([ABS Collection].[Customer Code] InList("COPART0032";"COPART0033";"COPART0034") And ([ABS Collection].[Crop Group]

InList("Cotton";"Field Crops";"Vegetables")))))

the formula is rite giving 0 value  but in total column iam getting 25200.

give the solution.