My son and I built the mouse bot project following the online directions and tried to used the pre-programmed programs to operate. When we turned on the bot following lesson 03A video and selected program #1 it just keep going in circles with no obstacles in its path (even with the variable resistor turned all the way "less sensitive"). Is something wrong with the RF sensors? I tried on multiple surfaces including wood and granite. I tried placing obstacles in the way and that did not help either. Thanks for any help.