Week nr is not the same in viewer and pdf

[orbair]

Hi All,

I have a strange situation. I use _week_of_year (current_date)-1 for showing last week in the title of the report. When I run my report all the data are calculated for W38, but the title is week 37. When I save this report in pdf, in the output the title is already week 38. I have played with the use local cache in the query -  set to NO , that resolved my issue, but can someone explain why happens this thing? If I create a report should I always use local cache no?

Thanks in advance