Need help with IHTML input button element

I'm trying to fill some values into text fields in
http://samples.thinkgeo.com/GeoCodeUSASampleApps/GeoCodeUSASample.aspx
.. but i'm not able to submit the reverse geocode button
programmatically. can anyone please help me with this?
following is the concerned part of the code:

//Supplying the Latitude Values for the location
MSHTML::IHTMLInputTextElementPtr lat= pAllElems->item("txtLatitude");
lat->value = "38.955466230591";

//Supplying the Longitude values for the location
MSHTML::IHTMLInputTextElementPtr lng= pAllElems->item("txtLongitude");
lng->value = " -95.2806172074041";

Sleep(5000);

//Programmatically submitting the reverse geocode button
MSHTML::IHTMLInputButtonElementPtr act1=pAllElems->item
("btnReverseGeocode");
action->form->submit();

.