Sure, try the following...

Insert Name Define

Name: BigNum

Refers to: =9.99999999999999E+307

Click Ok

Then try...

=LOOKUP(BigNum,CHOOSE({1,2},0,AVERAGE(IF(Daily!$A$ 4:$A$604Weekly!A4,IF(D
aily!$A$4:$A$604<=Weekly!A5,IF(Daily!$B$4:$B$604< "",Daily!$B$4:$B$604)))
)))

....confirmed with CONTROL+SHIFT+ENTER. The formula will return 0
instead of #DIV/0!. If you'd like the cell to be blank, you can custom
format the cell...

Format Cell Number Custom Type: [=0]""

Hope this helps!

In article ,
gimiv wrote:

It worked. Thanks again. One more thing. Is there a way to set it so
that if there are noe values to calculate, you don't get the #DIV/0!
error?