Undefined reference to class?

NetBeans interpret weird my code. In main function I have code:

SequenceAlignment align;
align.Alignment( local, seqs, argv[4], matrix)

But NetBeans show:

cpp:91: undefined reference to `SequenceAlignment::Alignment(std::basic_string<char, std::char_traits<char>, std::allocator<cha开发者_开发知识库r> >, std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >, char*, ScoreMatrix&)'

To be honest I do not know what to think. It works before, but now suddenly it doesn't.

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This is a linker error indicating that the linker can't find an implementation for SequenceAlignment::Alignment. Check to see that you indeed have an implementation of this function and that the code containing that implementation is indeed being compiled and linked.