I have a problem with the way dates are being displayed in the x-axis of an XY scatter.

The x-axis data is being read from a column with Date (dd/mm/yyyy (English UK)) format using =Data!$A$2:$A$803. The dates in the column start at 24/10/2008 up to 28/10/2011. The dates in the plot read 00/01/1900 to 18/06/1902. The format of the x-axis is also dd/mm/yyyy (English UK). What could be wrong?