Excel 2007 : Calculate percentage

Hi All

I need some urgent help with a formula that is trying to calculate percentage.

I have the following formula
=IF(ISERROR(COUNTIF(C7:C42,"Cut")/(COUNTIF(C7:C42,"<>N/A"))),"",IF(COUNTIF(C7:C42,"Cut")=0,IF(C44>0,1),COUNTIF(C7:C42,"Cut")/(COUNTIF(C7:C42,"<>N/A"))))

The above formula is trying to calculate the percentage of a process. Which can either be Cut, Sew, Foam, Trim, Inspected (QC), Development (Dev) and Delivery (Del)

My Problem is that when nothing is selected in a column I still get 100.00% or False instead of a zero or blank cell as can be seen in the sample file attached column D and F.

What I am trying to achieve is that if nothing has been selected for the column then 0.00 or blank cell is displayed. (Sample.xls file D19 to D25 should be 0.00% or Blank)

Otherwise if a process has been selected then the percentage of that process is calculated. But if say for instances all of Cut process has been completed for all items then the Cut process should read 100.00% and what ever percentage the next stages are at. (See Sample File C19 to C25)

Any help would be much appreciated.

Thanks

Mo