在GridView中要使成绩一列小于60字体显示红色时出错解决方案_ASP.NET

在GridView中要使成绩一列小于60字体显示红色时出错
代码如下：
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
if (Convert.ToInt32(e.Row.Cells[6].Text.Trim()) <= 0
|| Convert.ToInt32(e.Row.Cells[6].Text.Trim()) > 60)
{
e.Row.Cells[6].ForeColor = System.Drawing.Color.Red;
}
}

提示输入字符串出错。

------解决方案--------------------------------------------------------
e.Row.Cells[6].Text.Trim()是整型的字符串嘛？
看看e.Row.Cells[6].Text.Trim()值是什么？

C# code

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)  {  string test=e.Row.Cells[6].Text.Trim();//看看这里的值是什么？  if (e.Row.RowType == DataControlRowType.DataRow)  {    if (Convert.ToInt32(e.Row.Cells[6].Text.Trim()) <= 0  || Convert.ToInt32(e.Row.Cells[6].Text.Trim()) < 60)  {  e.Row.Cells[6].ForeColor = System.Drawing.Color.Red;  }   }
------解决方案--------------------------------------------------------
HTML code    <form id="form1" runat="server">    <div>        <asp:GridView ID="gv" runat="server" AutoGenerateColumns="false" onrowdatabound="gv_RowDataBound">        <Columns>            <asp:TemplateField>                <ItemTemplate>                    <asp:Label ID="lblGrade" runat="server" Text='<%#Eval("Grade") %>'></asp:Label>                </ItemTemplate>            </asp:TemplateField>        </Columns>        </asp:GridView>    </div>    </form>