Debug Assertion failed! 这是什么错误

CListCtrlPop类
CStringList* CListCtrlPop::SelectStringList(int number, CStringList *newstringlist)
{
    if(number<0)
    {
        MessageBox("stringlists.number<0");
        return NULL;
    }
    ASSERT(newstringlist!=NULL);

    CStringList* temp=m_strlist;
    m_iColumns=number;
    this->m_strlist=newstringlist;

    this->ClearListAllColumn();        

    int length=0;                     
    CString str;
    int* col_length=new int[m_iColumns];   
    for(int k=0;k<m_iColumns;k++)
        col_length[k]=8;
    for(int i=0;i<m_iColumns;i++)
    {
        this->m_listctrl->InsertColumn(i,m_strlist[i].GetHead()); //编译到这里出错
        col_length[i]=max(col_length[i],m_strlist[i].GetHead().GetLength());
        POSITION pos=m_strlist[i].FindIndex(1);
        for(int j=1;pos!=NULL;j++)
        {
            str=m_strlist[i].GetNext(pos);
            col_length[i]=max(col_length[i],str.GetLength());
        }
        m_listctrl->SetColumnWidth(i,col_length[i]*10);//LVSCW_AUTOSIZE_USEHEADER
    }
    for(k=0;k<m_iColumns;k++)
        length=length+col_length[k];
    m_listctrl->MoveWindow(0,0,length*10+18,this->m_rectShow.Height()-7);
    m_rectShow.right=length*10+26;
    delete [] col_length;
    return temp;
}
CDlgXSTH 类
bool CDlgXSTH::InitnListTH()
{
    CRect rect_nlist(10,350,700,650);
    this->GetClientRect(&rect_nlist);
    rect_nlist.top=150;
    rect_nlist.left+=10;
    rect_nlist.right-=10;
    rect_nlist.bottom=330;
    this->m_plistTH=new CListXSTH(m_bXsth,this->m_strPh);
    m_plistTH->Create(WS_CHILD|WS_VISIBLE|LVS_REPORT|
        WS_BORDER,rect_nlist,this,ID_NEWLISTLSXSDJ);
    //this->m_plistTH->OnParentMoved();

    this->m_plistTH->ModifyStyle(LVS_EDITLABELS, 0L);      
    m_plistTH->ModifyStyle(0L, LVS_REPORT);           
    m_plistTH->ModifyStyle(0L, LVS_SHOWSELALWAYS);      
    m_plistTH->ModifyStyle(0L, LVS_NOSORTHEADER);
//    m_plistTH->SetBkColor(RGB(0,200,200));
//    m_plistTH->SetTextBkColor(RGB(0,200,200));

    m_plistTH->ModifyStyle( LVS_OWNERDRAWFIXED,0L);
    m_plistTH->SetExtendedStyle( LVS_EX_FULLROWSELECT |      
    //    LVS_EX_HEADERDRAGDROP |      
        LVS_EX_GRIDLINES |   
    //    LVS_EX_ONECLICKACTIVATE |   
        LVS_EX_FLATSB                  
    //    LVS_EX_UNDERLINEHOT
        );   
    CString str;
    // 1、先产生numTitle列
//    m_plistTH->SetItemCount(20);
    int i=0;

    m_plistTH->InsertColumn( i, "商品编号" );
    m_plistTH->InsertColumn( 1, "商品名称" );
    m_plistTH->InsertColumn( 2, "仓库名称" );
    m_plistTH->InsertColumn( 4, "数量" );
    m_plistTH->InsertColumn( 5, "金额" );
    if(this->m_bXsth)
    {
    m_plistTH->InsertColumn( 3, "单价" );
    }
    else
    {
    m_plistTH->InsertColumn( 3, "进价" );
    }

// 2、插入1行

    m_plistTH->InsertItem(0,"");

    // 3、调整列宽
    RECT rect2;
    m_plistTH->GetWindowRect(&rect2);
    int wid = rect2.right - rect2.left;

    for( i=0; i<6; i++ )
    {

        m_plistTH->SetItemText(0,i,"");
        m_plistTH->SetColumnWidth( i, wid/6 );
    }
   
    m_plistTH->SetSubItemCanEdited(0);
    m_plistTH->SetSubItemCanEdited(1);
    m_plistTH->SetSubItemCanEdited(2);
    m_plistTH->SetSubItemCanEdited(3);
    m_plistTH->SetSubItemCanEdited(4);
    m_plistTH->SetSubItemCanEdited(5);

    m_plistTH->Invalidate(false);
    return true;
}
bool CListCtrlPop::Create(CWnd* parent)
{
    bool result = CDialog::Create(IDD,parent);
    this->ShowWindow(SW_HIDE);
    this->InitListCtrl();
    this->GetClientRect(&this->m_rectShow);   
    return true;
}