Some formulas do not work in Axlsx

[AlexCs389]

I am adding this formula to my .xlsx:

=BUSCARV(G2, 'Categorias'!A$2:C$3, 3, 0)

I add it this way to my worksheet:

sheet.add_row ["=BUSCARV(G2, 'Categorias'!A$2:C$3, 3, 0)"]

when I check my .xlsx in the cell I have this error #NOMBRE? and in
the entry line I have this =buscarv(F3,B2:C2,2,0)

I understand that this error #NOMBRE? is because the formula is misspelled but I cannot understand why the formula changes when you added it to the cell

How could I solve this?