Combine two cells in sumproduct

Question

I have below table

 ID      NEW                   ASSIGN
 123                       6/18/2015 15:48
 124    6/18/2015 11:13 
 125                       6/18/2015 9:22
 126                       6/17/2015 21:01
 127                       6/17/2015 20:30
 128                       6/16/2015 13:57
 129    6/15/2015 10:21 
 130                       6/15/2015 9:45
 131                       6/5/2015 8:26
 132    6/4/2015 11:02  
 133                       6/3/2015 16:01
 134                       6/18/2015 1:41
 135                       6/16/2015 3:37
 136    5/18/2015 18:36 
 137                       6/16/2015 3:33
 138                       5/11/2015 15:27

In cell E1:F1

 Aging  =SUMPRODUCT(--(A2:A17>128),--(A2:A17<136),

 --(NETWORKDAYS(C2:C17+0,TODAY()+0,0)<=30))

which gives me 5 as result.

Now, the requirement is to make use of NEW column value in place of blank cells in ASSIGN column.

Copy-paste NEW column values to ASSIGN cell is not an option, I am stuck with this.

Answer 1

Just wanted to check if @Byron answer in the comment works. It works, the result is 7.

{=SUMPRODUCT(--(A2:A17>128),--(A2:A17<136), --(NETWORKDAYS(IF(ISBLANK(C2:C17),B2:B17,C2:C17)+0,TODAY()+0,0)<=30))}