Update Query

I Have Three Table Here 

First Table :

Second Table

Third table 

I Have Update First Table Column OTD Like Query Here:

Update P Set OTD= (Select Case When max(DT)<= PD.DTWax Then 1 Else 0 End From PRCWax Where PRCNO=P.PRCNO Group By PD.PRCNO) From PRC As P Left Outer Join PRC_Day As PD ON PD.PRCNO=P.PRCNO 

But Sql Error Here

Each GROUP BY expression must contain at least one column that is not an outer reference

How It possible

Thank in Advance