function CapturarEnter(btn,event)
{
    if (document.all) 
    {
		if (event.keyCode==13)
		{
			event.returnValue=false;
			event.cancel=true;
			__doPostBack(btn,'')
		}
	}
    else if (document.getElementById)
    {
		if (event.which==13)
		{
			event.returnValue=false;
			event.cancel=true;
			__doPostBack(btn,'')
		}
	}
	else if (document.layers)
	{
		if (event.which==13)
		{
			event.returnValue=false;
			event.cancel=true;
			btn.click();
		}
	}
}