find customer payment using checknumber

@operator

I am trying to search Netsuite for CustomerPayment transactions based on checknumber, is this possible using checknumber as the only reference?

0 records are found, I am using the checknumber as the tranId to search for.

Using wsdl v2010_2_0

Search code is in c#:

TransactionSearch xactionSearch = new TransactionSearch();
TransactionSearchBasic xactionBasic = new TransactionSearchBasic();

xactionBasic.type = new SearchEnumMultiSelectField();
xactionBasic.type.@operator = SearchEnumMultiSelectFieldOperator.anyOf;
xactionBasic.type.operatorSpecified = true;
xactionBasic.type.searchValue = new string[1];
xactionBasic.type.searchValue[0] = "_customerPayment";

xactionBasic.tranId = new SearchStringField();
xactionBasic.tranId.@operator = SearchStringFieldOperator.@is;
xactionBasic.tranId.operatorSpecified = true;
xactionBasic.tranId.searchValue = checknumber;

xactionBasic.closed = new SearchBooleanField();
xactionBasic.closed.searchValue = false;
xactionBasic.closed.searchValueSpecified = true;