Correlation Coefficient DAX Measure Error (90 rolling)

[Anonymous]

Hi Experts

See sample file

https://www.dropbox.com/s/wewh7bgfu1x039d/Sample_Datapbix.pbix?dl=0 

Expect Result in Excel

https://www.dropbox.com/scl/fi/tw8jzia4624kzkk61usja/Test_Data.xlsx?dl=0&rlkey=zwt0opv6drj8z80i4ew4p... 

Kindly refer to the last 2 column in the table. I am trying to work out the 90 day rolling based on The Correlation Coefficient measure should start on the 10 may 2020 as that is data point 90 based on the Index Value.

The expected end results are shown in the Excel with the working calculation in Excel - i cannot work out why the results go wrong after the 10 May 2012.