Drop Down List problem

Greetings!

I'm having a problem with my drop down list control datasource. This is my code:

 string StrConn = "Select BusinessUnitName From NAI_BusinessUnits";
SqlDataReader Reader = NAI.DB.GetSQLReader(StrConn, gc.CONNSTR);

string str = NAI.DB.ErrorMessage;


ddlCategories.DataSource = Reader;


ddlCategories.DataBind();

 The problem is that I get = System.Data.Common.DbDataRecord listed 3 times in my drop down list control (this is the number of records I have in the table, so at least is getting this right)

By the way, if you don't see any code for open connection or readers is beacuse I use a library that provides that for me.

 Any ideas of what is causing this p ...