Design Tables in API

I am attempting to insert data into an assembly design table with no luck.  I am using C# and have created the data table.  When I attempt to use DesignTable::Attach, I keep receiving "false" (i'm assuming because the assembly does not have a design table yet).  Is there any way to create a design table from scratch in code?

DesignTable dt = (DesignTable)document.GetDesignTable();

ModelDocExtension mde = document.Extension;


bool attached = dt.Attach(); (Returns False)


bool does = mde.HasDesignTable(); (Returns False)

Thanks!

SolidworksApi macros