DAX formula gives a error. HELP!

[Anonymous]

When i try this dax formula;

Order really in = IF([ZSOER1.Intake date]="",[Order in],IF([ZSOER1.Intake date]-[Order in]<-30,[Order in],[ZSOER1.Intake date]))

it gives a error. It says; 

DAX comparisons do not support comparing Date values ​​with Text values. Consider using the VALUE or FORMAT function to convert one of the values.

On excel i tried about the same formula and it worked, but not in Power Bi.

I thought it had something to do with de columns ZSOER.Intake date and Order in. They are both dates type columns. But i don't know for sure if that is the problem. 

Does anyone knows the answer so he/she can help me?

[amitchandak · Accepted solution]

@Anonymous , for date datatype you can not check ""

IF( isblank([ZSOER1.Intake date]),[Order in],IF( datediff([ZSOER1.Intake date],[Order in], day)<-30,[Order in],[ZSOER1.Intake date]))

Negative datediff means , first date is bigger