Running Report from X++ Code

I am attempting to use the code show below to run the Inventory Value report from code. However, when I check the parameters collection, it is empty; and then I get parameter doesn't exist errors when I try to set parameter values. What am I missing here?

SrsReportRunController controller;

Map parms;

controller = new SrsReportRunController();

controller.parmLoadFromSysLastValue(false);

controller.parmReportName(ssrsReportStr(InventValue, Report));

controller.parmShowDialog(false);

parms = controller.parmReportContract().parmRdlContract().getParametersMap();

controller.parmReportContract().parmRdlContract().setValue('InventValue_FromDate', 1\7\2013);