Category Segmentation (Range Buckets) using direct query

My dataset has ID's with multiple orders. I am trying to calculate average discount across orders per ID.

And creating a column to bucket the averages of ID's. 

Bucket = Switch ( True(),
                           And( [Avg Discount %]>=-10 ,[Avg Discount %] < Sample[Fixed TMax Var 5%]) , "Green",
                           And( [Avg Discount %]>=Sample[Fixed TMax Var 5%],[Avg Discount %] < Sample[Fixed TMax Var 15%]) , "Yellow",
                           And(  [Avg Discount %] >= Sample[Fixed TMax Var 15%],[Avg Discount %] < 500),  "Red"
                         )

But when I am using the same formula to create a column. I am getting error "Function 'SUM' is not allowed as part of calculated column DAX expressions on DirectQuery models."

     I want to create a bar chart which shows the count of ID's in each segment. is there any alternate ways to achieve this?