C++ Can not create instance of abstract class

I have the following class:

(header)

struct udtMapping
{
    int ByteStart;
    int ByteCount;
    int iHPUnitID;
};

class clsMapping : public CBaseStructure
{
private:
    vector<udtMapping> m_content;

protected:

public:
    vector<udtMapping> &Content();
    void Add(int i1, int i2, int int3);
};

cpp file:

 vector<udtMapping> &clsMapping::Content()
 {
     return m_content;
 }
 void clsMapping::Add(int i1, int i2,int i3)
 {
     udtMapping n;
     n.ByteStart = i1;
     n.ByteCount = i2;
     n.iHPUnitID  = i3;
     m_content.push_back(n);    
     return;
 }

Now I wanted to use this class by saying

clsMapping nMapping;

But the compiler tells me "Can not create instance from abstract class".

I am not sure where I went wrong. Thank you for the help.

Edit: On request here is the CBaseStructure

 class CBaseStructure 
 {
 protected:
     virtual void ProcessTxtLine(string line) = 0;
     virtual void AfterLoad();
     virtual string CompactLine(string line);
 public:
     void Load(string file);
     void Load2(string file);
     void Load3(string file);
 };

CBaseStructure must be an abstract class. If you want to derive from it and you want a non-abstract class then you must override each pure virtual function that CBaseStructure declares. Clearly you didn't do that.

EDIT

CBaseStructure has one pure virtual function ProcessTxtLine. Your class must override that function.

There is nothing in your code that explains why you are inheriting from CBaseStructure, what do you thing it will do for you?