Financial Instrument Toolbox - DieboldLi Model

Can someone help me understand what's going on with my Matlab?

I've been working on the DieboldLi model shown on Matlab's site: "Fitting the Diebold Li Model". I got everything working fine with my own set of data but for some reason, after few hours, matlab stopped running the codes and gives me:

"Undefined variable "DieboldLi" or class "DieboldLi.firBetasfromYields" "Error in DieboldLi Model (Line 41) tmpCurveModel = ...

What happened? Did something get erased? Matlab can't find "DieboldLi.firBetasfromYields" code? If this code somehow got erased, do I need to reinstall matlab?

Please help,

thanks.