Hello I hope somebody could help me

at runtime I have an error:

terminate called after throwing an instance of 'GiNaC::parse_error'
what(): GiNaC: parse error at line 0, column 0: expected EOF, got: "["
[GiNaC::ex GiNaC::parser::operator()(std::istream&)(parser/parser.cpp:232)]

the code is:

for(int i=0; i< ramaPrim.size();i++)
   {
        parser reader;
       ex e = reader("ramaPrim[i]");
    }