As I was awaiting a response - I performed the test on a brand new sheet and got good results.
I believe the sheet that was sent to me had other format limitations upon it - that was keeping it from colorizing properly.
* I created the new sheet within the same file,
* Left row 1 for headers....
* Highlighted the blank row 2 ..... A2:Q2
* Conditionally format: =ISBLANK($E2)
* Copied the row down through row 600 ( which made the whole page "grey" )
* Went to the original sheet full of data, highlighted all
* Went to new sheet, EDIT > Paste Special > VALUES
and everything lit up beautifully with the appropriate rows GREY and all others left white....
THANKS for the help though! -- this ISBLANK for the range works perfectly on a clean sheet.