error in function module

Hi,

I want to create a function module which adds two numbers

n1, n2 and should get the result n3 = n1 + n2. I tried creating the FM in the following way but i got error. Kindly rectify.

In the import parameters

parameter name typing associated type

N1 TYPE I

N2 TYPE I

export parameters

N3 TYPE I

Source code

FUNCTION ZY.

*"----

""Local Interface:

*" IMPORTING

*" VALUE(N1) TYPE I

*" VALUE(N2) TYPE I

*" EXPORTING

*" REFERENCE(N3) TYPE I

*"----

N3 = N1 + N2.

ENDFUNCTION.

regards,

mahathi