jquerymobile: main (unrecognized role value)

I am a new starter to jQuery and I was just following a tutorial on YouTube using DW CS5.5 and I came across an error, 'jquerymobile: main (unrecognized role value)'.

The tutorial is here: https://www.youtube.com/watch?v=bsthKhTHguI

Take it to 2 minutes 52 seconds.

I have double checked what I have typed and cannot see an error, but using DW in 'split screen mode' it shows the 'jquerymobile: main (unrecognized role value)' as an error.