ZannGrid

Error while running the chunk
  [string "Mods/Addons/ZannGrid/Scripts/GridEx.lua"]:573: attempt to index a nil value
  func: __index, metamethod, line: -1, defined: C, line: -1, [C]
    func: GetRaidLeaderName, global, line: 573, defined: Lua, line: 570, [string "Mods/Addons/ZannGrid/Scripts/GridEx.lua"]
      func: UpdatePlayerInfo, global, line: 241, defined: Lua, line: 210, [string "Mods/Addons/ZannGrid/Scripts/GridEx.lua"]
        func: PlacePlayer, global, line: 468, defined: Lua, line: 450, [string "Mods/Addons/ZannGrid/Scripts/GridEx.lua"]
          func: FillGroup, global, line: 487, defined: Lua, line: 485, [string "Mods/Addons/ZannGrid/Scripts/GridEx.lua"]
            func: FillGrid, global, line: 495, defined: Lua, line: 491, [string "Mods/Addons/ZannGrid/Scripts/GridEx.lua"]
              func: RecreateGrid, global, line: 547, defined: Lua, line: 522, [string "Mods/Addons/ZannGrid/Scripts/GridEx.lua"]
                func: OnRaidChange, global, line: 566, defined: Lua, line: 564, [string "Mods/Addons/ZannGrid/Scripts/GridEx.lua"]
                  func: ?, ?, line: 1516, defined: Lua, line: 1514, [string "Mods/Addons/ZannGrid/Scripts/GridEx.lua"]