How do I exclude a value when using COUNTA?

Hello,

I am currently using the following formula to count cells that are not empty

=COUNTA (D4:D17)

However in this range there are certain values that I do not want to be counted.

I have tried this formula:

=COUNTA(D4:D17,"<>D")

But it counts incorrectly returning a sum of 3 when there should only be 1 because cells D14 and D15 are the only cells that have anything in the written in the cell and cell D14 has the letter "D" that I am trying to exclude from being counted.

I have also tried using COUNTIFS but as soon as I add a second value to count it says there are to many arguments. Which COUNTIFS are supposed to allow up to 250 arguments but it will only allow me to have one.

Any help would be greatly appreciated.