vector::erase returns incompatible iterator in debug build

#include <vector>

struct WordCoordinate {

   int    x;

    int y;

    int z;

};

struct Mypoint

{

   int x;

   int y;

};

int main()

{

    std::vector<WordCoordinate> m_worldCoorPoint;

    std::vector<Mypoint>    m_screenPoint;

    Mypoint point;

    for (int i=;i<=;i++)

    {

        WordCoordinate m_w;

        m_w.x=+i;

        m_w.y=+i;

        m_w.z=+i;

        m_worldCoorPoint.push_back(m_w);

        point.x = i+;

        point.y = i+;

        m_screenPoint.push_back(point);

        point.x = *i+;

        point.y = *i+;

        m_screenPoint.push_back(point);

    }

    int thershold =; // if distance low than thershold delete the point

    std::vector<WordCoordinate>::iterator itw=m_worldCoorPoint.begin();

    std::vector<Mypoint>::iterator it=m_screenPoint.begin();

    int idex = ;

    while(it!=m_screenPoint.end())

    {

        printf("delete point index %d\n",idex);

        printf("cur point (%d %d)",(*it).x,(*it).y);

        if( idex==)

        {

            it=m_screenPoint.erase(it,it+);

            itw=m_worldCoorPoint.erase(itw);

        }

        idex++;

    }

    system("pause");

    return ;

}