Hello! I have to create two members in my account dimension with data type "date", users should input a date, like : 11/03/2016, 30/05/2016.... and then I have to create a dynamic calc account that have a substraction between account 1 and account 2 with number of days. For example If user type in first account: 15/04/2016 and type on second account 3/05/2016 my third account should be: 18.
I create my member with data type: Date

and If I type in a form a date I have this error:

And finally I should have a third account that calculate number of days between first date and second date. I think that I should make with a dynamic calc...but I don't know.
Could you help me?
Thanks!