sink() within source() in R not working properly

Question

I have the following code:

source("file.R")

and file.R includes:

tab<-table(variable)
sink("variable.txt")
tab
sink()

However, the variable.txt file is empty. Any idea why ? I am using RStudio Version 0.99.902 and R version 3.3.1, on a Mac OS X El Capitan (Version 10.11.6).

A colleague of mine told me, this code works well for him under Windows.

Any help appreciated. Best regards !