My setEmbeddedData statement isn't working and I don't understand why

Hi,
I'm trying to record data about participants' screen resolution on my study. This is the statement that I am using:
Qualtrics.SurveyEngine.setEmbeddedData("xscreenresolution", screen.width);
However, whenever I run the study, xscreenresolution never appears in my recorded data. Did I do something wrong or are we not allowed to record screen resolution? Thanks in advance for any help.