Ok, let's get this straightened out...
formula in column I the column shows
1311 all the way down
formula in the formula bar is:
=DATEDIF(A5,(NOW()),"m")
That means the cells in column A are empty. An empty cell evaluates to 0 and
0 is the date serial number for 1/0/1900 (actually, the true value is Dec 31
1899 but Excel doesn't recognize dates before 1/1/1900. The 0th day of a
month refers to the *last* day of the previous month. There's a little more
to it than that but I don't want to go off into an entirely different
topic!).
So, change your formula to:
=IF(COUNT(A5),DATEDIF(A5,NOW(),"m"),"")
Copy down as needed.
OK, now your formatting...
You actually need to apply cf to both ranges, column A and column I.
If you want to keep column I "blacked out" until a date entry is made in
column A...
Select the range of cells of interest in column I. Let's assume the range is
I5:I20.
Goto the menu Format>Cells>Patterns tab>select Black>OK
With the range still selected, now apply the cf...
Goto the menu Format>Conditional Formatting
Select the Formula Is option
Enter this formula in the box on the right:
=COUNT(A5)
Click the Format button
Select the Patterns tab
Select No Color
OK out
Now, apply the cf to column A:
Condition 1:
Cell value is equal to 12 format is red
Condition 2:
Cell value is between 13 and 15 format is yellow
Cell value is greater than 15
Ok, what should happen if the cell value is greater than 15? I'm going to
take a guess and say you want the cell shaded GREEN.
Select the range in question. Let's assume the range is A5:A20
Conditional Formatting
Condition 1
Formula Is: =I5=12
Patterns tab>select a shade of RED
OK
Click the Add button
Condition 2
Formula Is: =AND(I5>=13,I5<=15)
Patterns tab>select a shade of YELLOW
OK
Click the Add button
Condition 3
Formula Is: =AND(COUNT(I5),I5>15)
Patterns tab>select a shade of GREEN
OK out