error

/home/mayank/Dropbox/Github/webgrass/src/MenuItem.cpp: In constructor ‘MenuItem::MenuItem(std::string)’:
/home/mayank/Dropbox/Github/webgrass/src/MenuItem.cpp:3:33: error: no matching function for call to ‘Wt::WMenuItem::WMenuItem()’
 MenuItem::MenuItem(std::string k)
                                 ^
/home/mayank/Dropbox/Github/webgrass/src/MenuItem.cpp:3:33: note: candidates are:
In file included from /home/mayank/Dropbox/Github/webgrass/src/MenuItem.h:17:0,
                 from /home/mayank/Dropbox/Github/webgrass/src/MenuItem.cpp:1:
/usr/include/Wt/WMenuItem:344:3: note: Wt::WMenuItem::WMenuItem(bool, const Wt::WString&)
   WMenuItem(bool separator, const WString& text);
   ^
/usr/include/Wt/WMenuItem:344:3: note:   candidate expects 2 arguments, 0 provided
/usr/include/Wt/WMenuItem:60:3: note: Wt::WMenuItem::WMenuItem(const string&, const Wt::WString&, Wt::WWidget*, Wt::WMenuItem::LoadPolicy)
   WMenuItem(const std::string& iconPath, const WString& label,
   ^
/usr/include/Wt/WMenuItem:60:3: note:   candidate expects 4 arguments, 0 provided
/usr/include/Wt/WMenuItem:52:3: note: Wt::WMenuItem::WMenuItem(const Wt::WString&, Wt::WWidget*, Wt::WMenuItem::LoadPolicy)
   WMenuItem(const WString& label, WWidget *contents = 0,
   ^
/usr/include/Wt/WMenuItem:52:3: note:   candidate expects 3 arguments, 0 provided
/usr/include/Wt/WMenuItem:30:14: note: Wt::WMenuItem::WMenuItem(Wt::WMenuItem&)
 class WT_API WMenuItem : public WContainerWidget
              ^
/usr/include/Wt/WMenuItem:30:14: note:   candidate expects 1 argument, 0 provided
make[2]: *** [CMakeFiles/wgrass.wt.dir/src/MenuItem.cpp.o] Error 1
make[1]: *** [CMakeFiles/wgrass.wt.dir/all] Error 2
make: *** [all] Error 2