Good morning Samuel
couple of pont - your post says you have a single record to add - viewing your excel file your record appears to be incomplete - i.e. your post 4 columns of data the file contains 32 -
second you have 2 options available to you when adding data to a tableau data set
1 add the data to you excel file and refresh the data
or add it as a separate file and append (Union) it to the existing data
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These step may help you, please follow:
If are using the extract of you data then first of all go to data source and then turn it to live.
Then Update the file(add data to the file) with the data you are having in new file and save it.
Make sure you are updating the one which is connected to the tableau.
Then open the tableau and refresh the data.
the data will be updated on tableau as well.
if you want to connect your data base directly with you tableau there may another steps.
The above steps are to update the data source held in excel.