Hash Marks Displayed In Date columns

Hi Experts

I have two date columns in my report.
But when i export this to excel spreadsheet i am getting
Hash Marks Displayed Instead of Dates on few of cells ....

I am really frustrated and tried everything by formatting date using to_char ,to_date in universe and also tried formatting
date in Infoview side.

But whenever i export this , I get ######## instead of dates .

Can anyone please advise ?