Summary sheet calc results change if rows added/deleted in detail spreadsheet

[Excel 2003] I have 2 spreadsheets: one to summarize data from a 2nd detail spreadsheet. I'm analyzing work order information for a service operation.

I'm using dynamic name ranges, as follows, for the detail:

WO_Num =OFFSET('WO Tracking Log'!$A6,0,0,COUNT('WO Tracking Log'!$A:$A),1)

Other detail data is defined as these examples show:

GM_X =OFFSET(WO_Num,0,8)
OpenDate =OFFSET(WO_Num,0,1)

All detail data begins in Row 6 in the detail spreadsheet.

In the Summary spreadsheet, it appears to make a difference where my calcs are located in order for my COUNTIF's to work correctly. As long as I keep my summary calc (to total the number of work orders in the detail) in Row 2 of the Summary, it works fine...but if EITHER I move my calc down a row OR if my detail drops down a row because a row was added above (where I have just header info), my summary totals change?!?! I don't understand.

Here are two examples of the calcs I'm using in the summary:

=COUNTIF(WO_Num,">0")
=COUNTIF(GM_X,"X")

Can someone tell me what is going on? What I'm doing wrong?