I have a masked textbox on my form which has a format of 'hh:mm'

However this gives me the time in 12 hour format whereas I want it in 24 hour format.

From reading on the web I understand that if I change the format to 'HH:mm' then this will give me what I want - However this doesn't work (all it does is change the format back to hh:mm)

Does anyone know how I can fix this ?