How to display dataset Field value in Page Header of SSRS report?

answer: http://social.msdn.microsoft.com/Forums/en/sqlreportingservices/thread/2e2bce70-43f5-4e36-9432-12fb762ccffe

Put the dataset feild value in any textbox inside the report body ,then in the report header textbox put the expression as

ReportItems!.Value ,where the textbox name should be the textbox you put in the report body having the dataset field value.