error when linearizing of powersystem

hi

I used simpowersystem to create model of kundur two area system but when i use power2sys command to extract system matrices i get this error: *Undefined function or method 'power_analyze_pr' for input arguments of type 'char'.

Error in ==> power2sys at 19 [varargout{1:nargout}] = power_analyze_pr(varargin{:});*