Changing Cell color back to no-fill with Conditional Formatting rule

[ave10]

I have two rules in a sheet I have. Once that checks if a range of cell rows (7:446) in column D equal any of the values listed in column A of a sheet titled "required_refs". If the values in those rows do match the values in the separate sheet, it'll turn that cell to a red fill background. The cell with the red fill background will eventually get a value in it. I want to setup an additional rule that checks if the cells in those rows are blank, if they are not blank, turn that cells backgroun color BACK to a no-fill. As i have it set up now, those cells stay red.

The formula for the first Rule: =ISNUMBER(MATCH($D7:$D446,required_refs!$A:$A,0))
The formula for the second rule: =LEN($F$7:$F$446)<0 I've also tried: =ISBLANK($F$7:$F$446)=FALSE

Does anyone know of any adjustments I can make to get the cells in the F column that have values in them to return back to a no-fill background color? Thanks!

 

[FDibbins]

For the 2nd (blank) CF rule, just reference that specific cell, not range...
=$F7=""

Not that this...
=LEN($F$7:$F$446)<0
will always show error (and therefor not trigger the CF), because a cell cannot contain a string of <0
Also, unless you enter that as an ARRAY (which CF does for you anyway), LEN() expects a s9ingle cell, not a range