ultraChart1.Axis.X.Labels.Orientation = Infragistics.UltraChart.Shared.Styles.TextOrientation.Horizontal;
to set the text orientation of the charts but this has not affect on the labels and the labels still vertical - is there something else that needs to go with this?
Your code should work for non composite charts, so I could guess that you are using composite charts. Please take a look at:
http://forums.infragistics.com/forums/p/4074/20187.aspx