Parameters in the SSRS Report

Hi,

I have duplicated the report Order line not invoiced. when i change the DP class which is duplication of Existing DP class. When I set the New DP class .New parameters( from contract class) or adding ..When i delete the parameter its not getting deleted from the Dataset 's parameter.

Also When i change the Parameter's datatype ..the changed datatype is not reflecting in the DataSet'sParameter.

How to resolve this.

Thanks in advance.