Descending Sort does not work

I am using Microsoft.CommerceServer.SearchOption class to sort a GridView 
either ASC or DESC.  The search is performed on a Profile class.

profile.ExecuteSearch() does not work correctly when SortDescending is set

to true. It always returns in ascending order. 

searchOption.SortProperties ="PropName";
searchOption.SortDescending=true;
profile.ExecuteSearch(entity, filter, searchOptions);

I also tried searchOption.SortProperties="[PropName]DESC" which raises an 
exception because it cannot find the property.

I used SQL profiles and it shows that in both scenarios the order is done
in 
ascending order.

Any help would be very much appreciated. Please note I am new to Commerce 
Server.