With so few information given you need a really good crystal ball to find the answer. Well, lets give it a start.
Which language? Ok, file extension is cpp, probably C++.
Which vector? Hard to say, lets assume the most simple case, its from the STL, so std::vector.
Which compiler, os, architecture? Unknown
Well, what can it be? Most probably again a C++11 issue, either the STL contains fancy C++11 stuff the parser doesn't understand or the vector value-type uses fancy C++11 stuff the parser doesn't understand.