Why are you using a parameter vs a relative date filter from you date dimension?
It is because I used two different data sources and different dashboard, and this will be used to calculate to last year at the same period. Is there any options?
We have to update parametrs manually since there is no automative process.
And the followiont method will some how help you.
1) Create a calculated field using the syntax as below.
Name: Today's Date
2) Right click on the above calculated field on the dimensions pane then click on "Create Parameter".
Another option is to create a single value list of dates from existing data via custom SQL as a new data source then use that to filter across the separate data sources.