Calculate function turned wrong

Hi everyone, 

Can you please help me to check why this Calculate function went wrong:

Week Amount = CALCULATE(sum(Merge[TotalAmount]),filter('Merge',Merge[YearWeeknum of PurchaseDay]))

Type = if([Week Amount]>9000,"high",if([Week Amount]>3000,"medium",if([Week Amount]>10,"low")))

Low = CALCULATE(counta(Merge[ID]),filter('Merge',[Type]="low"))



There are only 4 "low" in the measure "Type" but when in card visual, it shows there are 241 "low". 

Please check the data here: test

One more question, is there anyway to make "Type" able to slicer visual?

I look forward to learning from you. 

Many thanks and regards,

Cindy