Formula won't calculate when only some of the three variables are input

In column H:

=IF(ISERROR(L4-J4-K4),"",IF(OR(K4="0", K4=""), L4-J4, L4-J4-K4))

So, if formula is going to come up with an error, I don't need to know.

If it's not an error: L - J - K

Except that sometimes there isn't information in J or K, and the formula won't calcluate L - 0 - 0, unless I physically enter in zeros.

Turning the Zeros on under options doesn't help.
Forced (F9) or automatic calculation doesn't help.

I've also tried this formula

=IF(ISERROR(L4-J4-K4),"",IF(K4=""), L4-J4, L4-J4-K4))

and

=IF(ISERROR(L4-J4-K4),"", L4-J4-K4))

I don't want the people using this to have to enter in a plethora of zeros in order to force the calculation. What am I doing wrong?

I've attached workbook with the relevant information in it. You can see in the middle that if there is nothing entered, it won't work right.

formula is ok but there is text in c7 "^" clear the cells with delete

When I download and open the file I see no text in C7

And B7, B8 and B9 won't calculate unless you enter a number or 0 into C7, C8 or C9, respectively.

Try select column J and go to Data|Text to Columns and click Finish.

Repeat for column K and then for column L.

Then change the "0" in the formula to 0 without quotes...

e.g.

=IF(ISERROR(L4-J4-K4),"",IF(OR(K4="", K4=0), L4-J4, L4-J4-K4))

Those columns were somehow preformatted as text and so the numbers were actually text.

The Text to Columns (skipping to third window and setting column data format to General) resets the columns to general format (which makes numbers numbers). If you just hit finish at the start it is the same effect since General is default.

Then in the formula you have the 0 in quotes making it a text string, not numeric.