The reason your dash went blank is because "100%" means that 100% of the width and/or height of the dash is the new gauge. If you want a gauge that is one quarter of the dash, say the top left corner you would set the gauge settings to be Top 0%, right 50%, left 0%, bottom 50%. The 0% is referenced to starting from the left side and the top of the dash.
If you wanted a gauge that was the top right hand corner, the settings would be Top 0%, right 100%, left 50%, bottom 50%.

You can use all sorts of in between settinsg to change sizes and positions of the gauges.