Suitetalk How to get a customerPayment List filter by Date

@operator

                         TransactionSearch ts = new TransactionSearch();                            SearchEnumMultiSelectField so = new SearchEnumMultiSelectField();                          so.@operator = SearchEnumMultiSelectFieldOperator.anyOf;                          so.operatorSpecified = true;                          String[] sv = new String[1];                          sv[0] = "_salesOrder";                          so.searchValue = sv;                            SearchDateField sf = new SearchDateField();                          sf.@operator = SearchDateFieldOperator.on;                          sf.operatorSpecified = true;                          sf.searchValue = new DateTime(2008, 7, 5);                            TransactionSearchBasic tb = new TransactionSearchBasic();                          tb.type = so;                          tb.tranDate = sf;                                                    ts.payingTransactionJoin = tb;                                                   SearchResult r = service.search(ts); 

I'm doing something like this
But SearchResult return nothing
How can I solve this