Axolot Data

I wrote the following code:

XLS[0].AsFormula[2+3,Row]:= 'LOOKUP(HojaLecturas!'+A3+',Costos!$A$2:$B$244)';

when I open the sheet with Excel appear: #¿NOMBRE?

So, changing nothing, I click the Fx button on the cell , close the window and the function appear correctly

What am I missing in my code?

Thank you

Hello

Please provide a code sample that will compile.