web part error unhandled exception was thrown by the sandboxed code wrapper's

SPSite site = new SPSite("http://Myservername:4143/Lists/SaveMyCustomerServiceList/");
                site.AllowUnsafeUpdates = true;
                SPWeb web = site.OpenWeb();               
                SPList list = web.GetList("SaveMyCustomerServiceList");                                           
                SPListItem item = list.Items.Add();
                item["Title"] = "My Customer";
                item["Policy Types"] = Convert.ToString(ddPolicyType.SelectedItem.Text);
                item["Policy No"] = Convert.ToString(txtPolicyNo.Text);
                item["Name"] = Convert.ToString(txtName.Text);
                item["Date Of Birth"] = Convert.ToString(txtDOB.Text);
                item["Customer Contact No."] = Convert.ToString(txtMobileNo.Text);
                item["Email ID"] = Convert.ToString(txtEmailId.Text);
                item["Category"] = Convert.ToString(ddlCategory.SelectedItem.Text);
                item["Comments"] = Convert.ToString(txtComments.InnerText);
                item.Update();