Validate 2 date prompt in a report page

[gruposenda]

Hi :
Some body knows how to validate 2 date prompts ? I have a layout calculation with this code : if (ParamDisplayValue('pardateto') < ParamDisplayValue('pardatefrom')) then ('Error'), but it doesn´t work fine. It seems to validate only the day.

Thanks in advance.

 

[yphilogene]

ParamDisplayValue() may transform your date into a char like '27 Nov 2007'. In alphanumerical order:

'27 Dec 2007'<'27 Nov 2007' :S...

Maybe you should create a calculation in a Query, like:

if (?datefrom?<?dateto?) then ('ok') else ('error') end

and display it in a list