Thread:Extension talk:Cite/LUA Error With Cite

I have copied the templates and the error occurs in the references section Lua error in Module:Citation/CS1 at line 2058: attempt to call method 'getTitle' (a nil value).

Backtrace: (tail call): ? Module:Citation/CS1:2058: in function "chunk" mw.lua:553: ? (tail call): ? [C]: in function "xpcall" MWServer.lua:73: in function "handleCall" MWServer.lua:266: in function "dispatch" MWServer.lua:33: in function "execute" mw_main.lua:7: in main chunk [C]: ?

not sure how to fix this would be appreciate it, if someone could help