Date slicer and data filtering issue

Hi

I am new to Power BI and desparately need some help please.

I have 2 tables DateTable and Invoice data table (Jan2020). There is a link between DateTable and Jan2020 (invoice details) table (Date as the Key).

If I set the date slicer based on the dateTable's date field I get a different result for the Invoice totals (2.48M). And, if I change that to the date field from the Jan2020 table, then the correct invoice total (5.54) is shown. Not sure why like that.

I have attached both the pbix files and the excel file as well. -  https://1drv.ms/u/s!AtH8_xtZzGbXajif1stJLLvoVZU?e=bqcV8I

Can someone please have a look and let me know what I am doing wrong here. Really appreciate your help.

Thanks

Sam