Report Parameter Error(the value expression for the query parameter refers to non-existing report parameter . letters in the names of parameters must use the correct case)

 I use the @Region in the dataset query, then modify the parameter name from Region to region, then modify the @Region to @region in the dataset query. When we render the report, it throws an error message that “The Value expression for the query parameter '@region' refers to a non-existing report parameter 'Region'. Letters and names of parameters must use the correct case.” But we couldn’t find anything about Region in the Report Data tab.

the query parameter @region still use the =Parameters! Region.Value as value in the XML file. Even after removing them from the Data tab, the fields might still be in the and section.  Right-click the report in the Solution Explorer and go to "View Code" and double-check if Region is still present in those sections of the XML.

What's more, the issue may be caused by the cache. Please try to delete the reportname.rdl.data file in the report project folder before preview the report.