Count of customers that made an order of a certain value within a week

Hi,

My goal is to identify how many customers made sales that are less than $100, how many are from $100 - $500, how many are from $501 - $1000, and how many are $1000+ in a given year. I believe the best way to represent this data is a line graph with 4 different colour lines each indicating a specific category as listed above.

I tried doing this in Tableau but to no avail. It seems to just be giving me the following:

To categorize the sales amount into buckets, I created a calculated field with the following:

IF

SUM([Sales]) < 100 THEN '0 - 99'

ELSEIF

SUM([Sales]) <= 500 THEN '100 - 500'

ELSEIF

SUM([Sales]) <= 1000 THEN '501 - 1000'

ELSE '1000+'

END

For a bar graph, it seems to work perfectly so I'm not sure why it isn't for a line graph.

I've attached my twb file below using the sample-superstoredata provided by Tableau. Any idea on how to do this? Additionally, am I choosing the correct graph to represent the count of customers that made an order of a certain value within a week for a span of a year?