WildCard Functionality Error In SSRS

Hello All,

When i am calling the Report from ASP.NET getting the below error:
An error has occurred during report processing.
Query execution failed for data set 'dsOpenDefect'.
For more information about this error navigate to the report server on the local server machine, or enable remote errors


SP:

@DefectImpact varchar(max) = '',
@DefectNumber nvarchar(255) = '',
@DefectApplication nvarchar(255) = '',
@DefectBusinessFunction nvarchar(255) = '',
@DefectRelease nvarchar(255) = '',
@DefectStatus nvarchar(255) = '',
@Owner nvarchar(255) = ''
AS
set concat_null_yields_null OFF
Begin

declare @sql nvarchar(4000)
declare @whereClause nvarchar(max)
declare @sqlWhere varchar(max)
declare @Debug nvarchar(max)

select @sql = '
SELECT Defect.DefectNumber, Defect.DefectApplication, Defect.DefectBusinessFunction,
Defect.DefectRelease, Defect.DefectStatus, Defect.Owner, Defect.DefectImpact FROM Defect '

Set @sqlWhere = ''

if @DefectImpact <> '' or @DefectImpact IS NULL
begin
set @whereClause = ' where DefectImpact '
set @whereClause = @whereClause + ' = ''' + @DefectImpact + ''''
end

set @sqlWhere =@sql + @WhereClause

PRINT @sqlWhere
EXEC(@sqlWhere)

End


ASP.NET Code:

ReportParameter[] parm = new ReportParameter[7];
parm[0] = new ReportParameter("DefectImpact", txtValue3.Text.ToString());
parm[1] = new ReportParameter("DefectNumber", txtValue3.Text.ToString());
parm[2] = new ReportParameter("DefectApplication", txtValue3.Text.ToString());
parm[3] = new ReportParameter("DefectBusinessFunction", txtValue3.Text.ToString());
parm[4] = new ReportParameter("DefectRelease", txtValue3.Text.ToString());
parm[5] = new ReportParameter("DefectStatus", txtValue3.Text.ToString());
parm = new ReportParameter("Owner", txtValue3.Text.ToString());

RptViewer.ProcessingMode = Microsoft.Reporting.WebForms.ProcessingMode.Remote;
RptViewer.ServerReport.ReportServerUrl = new System.Uri("http://RSName/ReportServer");
RptViewer.ShowParameterPrompts = false;
RptViewer.ServerReport.ReportPath = "/Reports/Subbu_Sample";
RptViewer.ServerReport.SetParameters(parm);
RptViewer.ServerReport.Refresh();


Can anyone please help me in this regard.

Thanks,
SR.