Exception has been thrown by the target of an invocation

[hstas]

I deploy report on US customers and one of them obtain following exception:

"Exception has been thrown by the target of an invocation"

between this part of code
{
Stimulsoft.Report.StiReport rep = Stimulsoft.Report.StiReport.GetReportFromAssembly(repname,true);
rep["ParamName"] = value;
rep.Render(true);
rep.Show();
}

Any ideas why?

[Vital]

Please check following items:

1. Versions of report engine
2. Version of report dll (must be equal to version of report engine);
3. Name of ParamName (case sensitive)

Please provide full error message (include stack of calling).

Thank you.