Error when generating report with Excel formula

Hello. I'm getting this error when using an Excel formula on my report. My guess is that it's not reading WORKDAY.INTL() as one function, resulting in the following message:

Warning:  Could not find named cell WORKDAY when parsing formula ROUNDDOWN(WORKDAY.INTL($E3,K3)-$E3-(K5-1),0) in cell XlsFormulaReport!P3

And then it generates the .xls file and in the cell I get:  =#NAME?

How can I solve this?
Thank you.