Populate Dynamic Dropdown values based on Radio button in the Infopath form 2007

The below Dataconnection name is TestConn.Create dataconnection in the Infopath form

the List GUIid is {46A48934-00D5-4914-8EF2-E012AD40343C}

http://star:111/sites/pf/_vti_bin/owssvr.dll?Cmd=Display&List={46A48934-00D5-4914-8EF2-E012AD40343C}&XMLDATA=TRUE&noredirect=true

set the dataconnection in the VSTA code

First write the code in the button changed event
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XPathNavigator root = MainDataSource.CreateNavigator();
// Get the value for the selected department string Filter = "HC";
// Clear the last selected value in the Months drop-down list box root.SelectSingleNode("//my:Months", NamespaceManager).SetValue("");
// Retrieve the data connection bound to the HC radio button FileQueryConnection con = (FileQueryConnection)DataConnections["TestConn"];
// Change the location of the data connection to point the XML file // returned by the owssvr.dll with a filter on department con.FileLocation = @"http://star:111/sites/pf/_vti_bin/owssvr.dll" + "?Cmd=Display&List={46A48934-00D5-4914-8EF2-E012AD40343C}" + "&XMLDATA=TRUE&FilterField1=FName&FilterValue1=" + Filter;
// Query the data connection to fill the Months drop-down list box with items con.Execute();


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Second write the code in the button changed event
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XPathNavigator root = MainDataSource.CreateNavigator();
// Get the value for the selected department string Filter = "NI";
// Clear the last selected value in the Months drop-down list box root.SelectSingleNode("//my:Months", NamespaceManager).SetValue("");
// Retrieve the data connection bound to the NI radio button FileQueryConnection con = (FileQueryConnection)DataConnections["TestConn"];
// Change the location of the data connection to point the XML file // returned by the owssvr.dll with a filter on department con.FileLocation = @"http://star:111/sites/pf/_vti_bin/owssvr.dll" + "?Cmd=Display&List={46A48934-00D5-4914-8EF2-E012AD40343C}" + "&XMLDATA=TRUE&FilterField1=FName&FilterValue1=" + Filter;
// Query the data connection to fill the Months drop-down list box with items con.Execute();