Passing Date Prompt from DAshboard to Bex Queries

Dear All,
I am trying to pass a date as variables to a qBex connection in SAP Dashboard. I use text input boxes to plug the dates into my selected spreadsheet cells, unfortunately the query runs and I get no data.
 
I have tried to use this format :
 
01012016
20160101
 
01/01/2016
2016/01/01
 
01.01.2016
2016.01.01
 
01 01 2016
2016 01 01
 
Which kind of date format I have to pass to the qBex in order to retrieve the data ?
 
Best Regards,
MJ