Error with DATEDIF

[JMST]

Hi guys!

I'm building the following measure:

Last30Days =
IF(
DATEDIFF('Product Properties' [Last inventory date], 'Product Properties'[Report Date],DAY) <=31,
TRUE(),
FALSE()
)

And I obtain the following error: It is impossible to determine a unique value for the "Last inventory date" column in the "Product Properties" table. 

Could someone help me with this error?

Thanks!

[vk_pbi]

The reason is that, the last inventory date may have repeated values.. I think you can wrap it with MAX to handle this