I found this code on this NG and used it successfully several times.
But I have modified it slightly, to use a different formula and It returns
an error: Application Defined or Object Defined Error.

I don't know what this means.

This is the code which I sourced from Don Guillet:

Sub balance()' I use for a running balance in a checkbook.
Set frng = Range("b3:b" & Range("a65536").End(xlUp).Row)
With frng
..Formula= "vlookup(a1,sheet2!a2:z200,2,false)"
' .Formula = "=h7+d8"
.Formula = .Value 'changes the formula to value
End With
End Sub


This is my modified code:
Sub Balance()
Set frng = Range("L4:L" & Range("B65536").End(xlUp).Row)

With frng
..Formula = "=IF(K4=1,"",F4-D4)"
' .Formula = "=h7+d8"
.Formula = .Value 'changes the formula to value

End With

End Sub
I have used several successful variations to my version of the code, but
this formula "=IF(K4=1,"",F4-D4)" gives me the problem.

I don't know much about writing macros.
Can anyone offer an explanation and a fix for this please.
Cheers Paul