Get stuck with VAR.S Function

Hello everyone... I am begginer in PBI Desktop. Please Help me
I have two table one is the fact table ("Calc_Blom_PriceData") , and one is the DimDate

I try to find Variance data that dates back 100 days for every record
But its always get error
Please Help me to solve this , and please let me know where did I do wrong ??

Thanks before
This is the link for the PBI desktop file and excel File

https://drive.google.com/open?id=1T00a5-iazpFv5Si14_vCrPxcapO00IfO&fbclid=IwAR0fBDY2XnTCfdzrQy2LEIRYN2-V9A4c4RSjXGNC8aQxAQHn3Ng6urBFszc