problem with multiplying in CR formula

i use

isnumber({table.field1}) * isnumber({table.field2})

first it was working just fine then a months late it come up with an error 'string is non-numeric'. after searching around i found a solution which look like this after i generated it to my code

((If NumericText ({table.field1}) then ToNumber ({table.field1}) else 0) * (If NumericText ({table.field2}) then ToNumber ({table.field2}) else 0))

but it does not multiply, it's only printing table.field1 value on report. where did i do wrong?.

thanks before