动态设置datagrid的alignment的属性为Center总出错,怎么回事?

我在动态从数据库里取数据以后设置datagrid的alignment的属性为Center总出错,怎么回事?提示信息为:D:\My Documents\Visual Studio Projects\compu\Form1.cs(253): 名称“Center”在类或命名空间“compu.Form1”中不存在,去掉columnstyle1.Alignment=Center;就可以执行但不能按要求完成代码如下阿:
private void Form1_Load(object sender, System.EventArgs e)
{
DataGridTableStyle mytable=new DataGridTableStyle();
mytable.MappingName="computer";
DataGridTextBoxColumn columnstyle1=new DataGridTextBoxColumn();
columnstyle1.MappingName="dept";
columnstyle1.HeaderText="部门编号";
         columnstyle1.Width=80;
columnstyle1.Alignment=Center;
mytable.GridColumnStyles.Add(columnstyle1); DataGridTextBoxColumn columnstyle2=new DataGridTextBoxColumn();
columnstyle2.MappingName="dno";
columnstyle2.HeaderText="电脑编号";
columnstyle2.Width=60;
                           columnstyle1.Alignment=Center;
mytable.GridColumnStyles.Add(columnstyle2); DataGridTextBoxColumn columnstyle3=new DataGridTextBoxColumn();
columnstyle3.MappingName="dname";
                  columnstyle3.HeaderText="电脑名称";
columnstyle3.Width=60;
mytable.GridColumnStyles.Add(columnstyle3);            DataGridTextBoxColumn columnstyle4=new DataGridTextBoxColumn();
columnstyle4.MappingName="cuser";
columnstyle4.HeaderText="英文名称";
columnstyle4.Width=60;
mytable.GridColumnStyles.Add(columnstyle4);            DataGridTextBoxColumn columnstyle5=new DataGridTextBoxColumn();
columnstyle5.MappingName="puser";
columnstyle5.HeaderText="中文名称";
columnstyle5.Width=60;
mytable.GridColumnStyles.Add(columnstyle5);            DataGridTextBoxColumn columnstyle6=new DataGridTextBoxColumn();
columnstyle6.MappingName="moniter";
columnstyle6.HeaderText="显示器";
columnstyle6.Width=90;
mytable.GridColumnStyles.Add(columnstyle6);            DataGridTextBoxColumn columnstyle7=new DataGridTextBoxColumn();
columnstyle7.MappingName="cpu";
columnstyle7.HeaderText="C P U";
columnstyle7.Width=70;
mytable.GridColumnStyles.Add(columnstyle7); DataGridTextBoxColumn columnstyle8=new DataGridTextBoxColumn();
columnstyle8.MappingName="hd";
columnstyle8.HeaderText="硬盘";
columnstyle8.Width=70;
mytable.GridColumnStyles.Add(columnstyle8); DataGridTextBoxColumn columnstyle9=new DataGridTextBoxColumn();
columnstyle9.MappingName="sd";
columnstyle9.HeaderText="内存";
columnstyle9.Width=60;
mytable.GridColumnStyles.Add(columnstyle9); DataGridTextBoxColumn columnstyle10=new DataGridTextBoxColumn();
columnstyle10.MappingName="mk";
columnstyle10.HeaderText="显示卡";
columnstyle10.Width=80;
mytable.GridColumnStyles.Add(columnstyle10); DataGridTextBoxColumn columnstyle11=new DataGridTextBoxColumn();
columnstyle11.MappingName="ip";
columnstyle11.HeaderText="IP地址";
columnstyle11.Width=90;
mytable.GridColumnStyles.Add(columnstyle11); dataGrid1.TableStyles.Clear();
dataGrid1.TableStyles.Add(mytable);
SqlConnection conn=new SqlConnection("server=tian;database=factory;uid=sa;password=sys1369");
conn.Open();
SqlDataAdapter adpt=new SqlDataAdapter("select dept ,dno,dname,cuser,puser,moniter,cpu,hd,sd,mk,ip from computer",conn);
DataSet dt=new DataSet();
adpt.Fill(dt,"computer");
dataGrid1.DataSource=dt;
dataGrid1.SetDataBinding(dt,"computer");
textBox1.DataBindings.Add("Text",dt,"computer.dept");



}