Issue creating customer sort with special text column

Hi Peps,

I'm trying to create a customer sort with the help of dimension table, it worked for number and text perfectly. What turns it down is when using a special charter as a parameter to sort, for instance when I'm trying to create a column "Per_Day" which ranges from the -12 and +12 days from Presales (middle of Per_Day column) it's not sorting as I expect it to be, though I've defined relationship with the base table and sort this table with "Order"

I'm getting something like below

The outcome should be something like:

Any help in this regard will be much appreciated!

Thanks,
Atul