Macro creating chart gallery giving problem

Hi,
I have problem with a macro that creates chart gallery.
I have a chart gallery file as gallery.xls. I write all the charts from this
gallery to xlusrgal.xls in a macro. The macro runs fine and I get my chart
styles as well. However there is a problem, when I go to Excel and create a
new chart my chart styles are seen under custom types-->User defned. However
I lost charts under Custom types-->Built-in. Here's the code that I am using.

Application.AddChartAutoFormat sht, sht.Name,"Custom chart"

Any help on this is much appreciated. I am using Excel 2003 and Windows XP.

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Pranav Vaidya
VBA Developer
PN, MH-India