It looks like you are also using a dimension Country, is this correct? [edit: I see, that's what you posted in your first line]
Since your 4 expressions will only produce output for 1 dimension value each, you'll get an effect like above (i.e. the gaps are due to 'missing bars' for the other 3 expression per country dimension value).
Try removing the dimension completely (or change your 4 expression to 1).