Nprinting filter not working properly ?

[#1]

Dear all,

I have a strange issue...I built a report with the verify filter option activated.

But when I run it.. I have a warning

but when I untick the verify filter .. everything works well..

The reports is very easy.. I have only one table..

The currencyList field is in an "island table"...

I have a variable "vAnalysisCurrency"  =if (GetPossibleCount(CurrencyList)<>1 ,'EUR', MinString(CurrencyList))

to convert all local currency to the reporting  Currency ..

is anybody have an idea to help me ?

[#2]

I have found a solution.

1/ In the QlikView App I replaced the "List Box"  (with only one selection value ) by an "Input Box" with a Field list

"=concat(distinct CurrencyList,';')"

2/ In the Nprinting I created a "Filter variable" with the following syntax :=MinString(CurrencyList)

It seems to work.. but I do not understand why in my first scenario  it's not working