SharePoint 2013 Calculated Field result with "1722947040" value when it was supposed to be an empty string

Hi Everyone,

I have a List with column "Active"(Boolean), "Title", "ActiveTitle". The ActiveTitle is a CalculatedField with Formula: =IF(Active, Title, ""). The problem I have is when the item is Inactive (Active=0), ActiveTitle is always displayed as "1722947040", not ""(Empty string).

For Example:

Title  Active ActiveTitle

Tes1    1       Test1

Test2   0       1722947040 (Supposed to be "")

Anyone know how to fix this?

I test on another sharepoint server and it changed to "518264288", but still not an empty string.

Thanks