Performing Ordinary Kriging in SAGA via QGIS SEXTANTE Plug-in?

I'm trying to learn how to apply the kriging analysis in QGIS using the SEXTANTE plug-in and SAGA tools. It appears that I have my SEXTANTE and SAGA folders configured properly according to the user guide. I've never used a kriging function before and I can't find a good resource from SAGA explaining the different input parameters. Does anyone have experience using the ordinary kriging tool in SAGA that can provide advice or a reference? I'm currently getting the following error message in QGIS:

An error has occured while executing Python code: 
Traceback (most recent call last):   
File "C:/Documents and Settings/PS/.qgis/python/plugins\sextante\gui\ParametersDialog.py", line 137, in accept if self.setParamValues():   
File "C:/Documents and Settings/PS/.qgis/python/plugins\sextante\gui\ParametersDialog.py", line 91, in setParamValue if not self.setParamValue(param, self.paramTable.valueItems[param.name]):   
File "C:/Documents and Settings/PS/.qgis/python/plugins\sextante\gui\ParametersDialog.py", line 129, in setParamValue return param.setValue(widget.getValue())   
File "C:/Documents and Settings/PS/.qgis/python/plugins\sextante\parameters\ParameterExtent.py", line 11, in setValue if value is None: NameError: global name 'value' is not defined