Problem: Report only come out once in my application

When starting the Report which is made with ReportSmith V2.5.1 in my application, It is OK for the first time, but It dose not come out if I start the report again and again in my application. There is no error message.

The details is as follows:
1) Application
There is a report control named Report1 and a starting report button in my Delphi application. Before starting the report, there are some report parameters to be setup as follows:
Report1.InitialValues.Add(S1);
Report1.InitialValues.Add(S2);
Report1.InitialValues.Add(S3);
Report1.Preview := True;
Report1.run;
 
2)Report
There are several report variables S1, S2, S3 in the report. These variables are SQL clause. Such as FROM,WHERE,ORDER BY etc.

Without these report variables (SQL is fixed), the report can be started as many times as you want in the application.

With these report variables, the ReportSminth Run_Time Viewer can be started repeatedly, but the report come out only once, and no more come out again even though you close the report and keep clicking the starting report button in the application unless you quit the application and start it again.

Thanks and Regards