SYMPTOM
A graph with different series options does not retain its formatting in Strategy Distribution Services 9.4.x - 10.x when sent as an Excel attachment.
Original Graph

Below is the graph after being sent through Distribution services as an Excel attachment. The graph is no longer a line and bar graph combination, it only displays bars.

CAUSE
This behavior can be expected when the Excel version preference on Strategy Web is set to 'Excel 2003/XP'
ACTION
Set the version preference on Strategy Web to 'Excel 2007 or newer versions'