c++ - LNK2019: unresolved external symbol in VS unit-testing

I get the error as stated in the title. I ensured the
following:
- The Include directory, include library and additional include
directory are set correctly
- In the properties, Subsystem is set to CONSOLE

Comments to my code:
LifeLib is a
project that contains classes of that I want to test some methods. The classes are
defined in namespace LifeLib. One of them is StornoTafel. testVariables is NOT defined
in any namespace.
I get the linking error 3 times, for 2 constructors and 1
method in StornoTafel (noted in the
code).

//project
            Tester

#include "stdafx.h"
#include
            "CppUnitTest.h"

#include
            "../LifeLib/StornoTafel.h"
#include
            "../LifeLib/testVariables.h"

using namespace
            Microsoft::VisualStudio::CppUnitTestFramework;

namespace
            Tester
{ 

 TEST_CLASS(AggSelTest)
 {

            public:
 LifeLib::StornoTafel stornoTafel_; // LNK2019

            LifeLib::StornoTafel *stornoTafel_; // no error, but I need an instance and not a
            reference to proceed -> see init method
 LifeLib::testVariables test_vars_;
            // everything is fine

 TEST_METHOD_INITIALIZE(init) {

            stornoTafel_ = StornoTafel(test_vars_.lapseProb); // when this line is commented out I
            only get the first error (see below)
 }


            }
}

// testVariables.h
#pragma
            once
#include 
#include
            

class testVariables
            {
public:

 testVariables() {};
// here are a
            lot of vectors with values for testing purposes
std::vector
            _lapseProb= {0,1,2}; // [...]
};

//
            StornoTafel.h
#pragma once
#include
            "masterheader.h"

namespace LifeLib {

 class
            StornoTafel {
 public:

 StornoTafel();
            //LNK2019
 StornoTafel(std::vector ProbabilityOfLapseInYearT);
            //LNK2019

 StornoTafel(const StornoTafel &obj); //no
            error

 StornoTafel operator=(StornoTafel const& rhs);
            //LNK2019


 //! \name Getter
 //@{ 

            const std::vector& Stornowahrscheinlichkeit() const;

            //@}
 protected:
 std::vector
            Stornowahrscheinlichkeit_;
 };
 inline const
            std::vector& StornoTafel::Stornowahrscheinlichkeit() const
            {
 return Stornowahrscheinlichkeit_;

            }

}

//StornoTafel.cpp
#include
            "StornoTafel.h"

LifeLib::StornoTafel::StornoTafel()
            {
}

LifeLib::StornoTafel::StornoTafel(std::vector
            ProbabilityOfLapseInYearT) {
 Stornowahrscheinlichkeit_ =
            ProbabilityOfLapseInYearT;

}

LifeLib::StornoTafel::StornoTafel(const
            StornoTafel &obj) {
 Stornowahrscheinlichkeit_ =
            obj.Stornowahrscheinlichkeit_;
}

LifeLib::StornoTafel
            LifeLib::StornoTafel::operator=(StornoTafel const& rhs) {

            Stornowahrscheinlichkeit_ = rhs.Stornowahrscheinlichkeit_;
 return
            *this;
}


//masterheader.h
#pragma
            once
#include 
#include
            
#include 
#include
            

#include 
#include
            

errors
in detail:

1. LNK2019 unresolved external symbol "public:
   __cdecl
   LifeLib::StornoTafel::StornoTafel(void)"
   
   (??0StornoTafel@LifeLib@@QEAA@XZ) referenced in function "public:
   __cdecl
   AggSelTester::AggSelTest::AggSelTest(void)"
   (??0AggSelTest@AggSelTester@@QEAA@XZ)



2. LNK2019
   unresolved external
   symbol "public: __cdecl
   LifeLib::StornoTafel::StornoTafel(class
   std::vector >)"
   
   (??0StornoTafel@LifeLib@@QEAA@V?$vector@NV?$allocator@N@std@@@std@@@Z)
   
   referenced in function "public: void __cdecl
   
   AggSelTester::AggSelTest::init(void)"
   
   (?init@AggSelTest@AggSelTester@@QEAAXXZ)


3. LNK2019
   unresolved external
   symbol "public: class LifeLib::StornoTafel
   __cdecl
   LifeLib::StornoTafel::operator=(class LifeLib::StornoTafel const
   &)"
   
   (??4StornoTafel@LifeLib@@QEAA?AV01@AEBV01@@Z) referenced
   in function
   "public: void __cdecl
   AggSelTester::AggSelTest::init(void)"
   
   (?init@AggSelTest@AggSelTester@@QEAAXXZ)

Why do they
arise?