RPG to Excel - getFitToPage Compile Error

I am trying to retrieve the value for the FitToPage setting in the excel
spreadsheet.

From the documentation on the Class, it says that getFitToPage is supposed

to return a value, however I am getting a compile error:
RNF5403 30 1 The prototyped call cannot be used in an expression
because it does not return a value.

Is there something wrong with my prototype setup here?

D SHEET_CLASS...
D C 'org.apache.poi.ss.usermodel-
D .Sheet'

D SSSheet_getFitToPage...
D PR EXTPROC(*JAVA
D : SHEET_CLASS
D :'getFitToPage')
D thisFitToPage S n

thisFitToPage = SSSheet_getFitToPage(sheet);