Problem creating managed property mappings programmatically

Hi,

I need help with this method to create mapping between managed property and crawled property.

        public static void CreateMapping(SPWeb web, SearchAdmin.SearchObjectLevel level, string categoryName,
                                         string managedPropertyName, string crawledPropertyName)
        {
            // Get search owner (search scope)
            SearchAdmin.SearchObjectOwner searchOwner = new SearchAdmin.SearchObjectOwner(level, web);

            // Get search service app proxy
            SearchAdmin.SearchServiceApplicationProxy searchProxy = GetSearchProxy(web);

            if (searchProxy == null)
            {
                return;
            }

            // Get managed property
            SearchAdmin.ManagedPropertyInfo managedProperty = searchProxy.GetManagedProperty(managedPropertyName, searchOwner);
            SearchAdmin.ManagedProperty mp = new SearchAdmin.ManagedProperty();

            // If managed property exists
            if (managedProperty != null)
            {
                //SearchAdmin.SearchObjectOwner SsaOwner = new SearchAdmin.SearchObjectOwner(SearchAdmin.SearchObjectLevel.Ssa, web);

                // Get crawled property by name
                System.Collections.Generic.List<SearchAdmin.CrawledPropertyInfo> crawledProperties = searchProxy.GetAllCrawledProperties(crawledPropertyName, categoryName, 0, searchOwner);
                //SearchAdmin.CrawledPropertyInfo crawledProperty = searchProxy.GetCrawledProperty(categoryGuid, crawledPropertyName, 0, false, searchOwner);

                // If crawled property exists
                if (crawledProperties.Count > 0)
                {
                    // Set mapped crawled properties
                    managedProperty.MappedCrawledProperties = new System.Collections.Generic.List<SearchAdmin.CrawledPropertyInfo>();
                    managedProperty.MappedCrawledProperties.Add(crawledProperties[0]);

                    // Update managed property
                    searchProxy.UpdateManagedProperty(managedProperty, searchOwner);
                }
            }
        }

Any suggestion?

Thanks!