可能是重复问题：
ASP.NET中第一次点击按钮不触发OnClick事件？
<asp:Button ID="buttonSub" runat="server" CssClass="btn9"
OnClick="buttonSub_Click" OnClientClick="return confirmation();" Text="Next" />
<asp:Button ID="ButtonCancel" runat="server"
CssClass="btn9" OnClick="ButtonCancel_Click" CausesValidation="false" Text="Cancel" />
try
{
//Resize the Photo Image
ResizePhoto();
//Resize the Company Logo Image
ResizeCompanyLogo();
bool ErrorGuid = false;
string LoginNameChecking = "<MortValidLoanOfficerLoginName><LoginName>" + textboxLoginName.Text.Trim() + "</LoginName></MortValidLoanOfficerLoginName>";
dsLogincheck = objGeneric.GenericMethod(LoginNameChecking, "MortValidLoanOfficerLoginName", out ErrorGuid);
if (Convert.ToInt32(dsLogincheck.Tables[0].Rows[0][0]) == 1)
{
Session["firstname"] = textboxFirstName.Text;
Session["lastname"] = textboxLastName.Text;
Session["loginpassword"] = textboxLoginPassword.Text.Trim();
Session["reenterpassword"] = textboxReEnterPassword.Text.Trim();
Session["emailaddress"] = textboxEmailAddress.Text.Trim();
Session["loanofficertype"] = DropDownListLoanOfficerType.SelectedItem.Value.Trim();
Session["companyname"] = textboxCompanyName.Text.Trim();
Session["companyurl"] = textboxCompanyURL.Text.Trim();
Session["registrationperiod"] = DropDownListRegistrationPeriod.SelectedItem.Value.Trim();
Session["RegistrationAmount"] = Convert.ToString(100 * int.Parse(DropDownListRegistrationPeriod.SelectedItem.Value));
Session["str"] = "yes";
textboxLoginName.Text = "";
ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "aa", "<script>alert('login name already exists Please enter another login name');</script>", false);
Response.Redirect("~/LoanOfficerRegistration.aspx");
}
else
{
Server.Transfer("CreditCardInfo.aspx", true);
}
}
catch (Exception ExeptionMessage)
{
}
protected void ButtonCancel_Click(object sender, EventArgs e)
{
Session["LoginValidation"] = null;
Response.Redirect("~/Logon.aspx");
}
这是一个注册表单，取消按钮在第一次点击时不起作用。当提交按钮被点击一次后，再点击取消按钮两次才能生效，否则将无法取消。
请提供解决此问题的方案。
protected void Page_Load(object sender, EventArgs e) {
if (!IsPostBack)
{
GetLoanOfficerid();
textboxFirstName.Focus();
//Values Assigning to Registration Page Controls if Login Name Already Exists
if (Session["str"] == "yes")
{
Page.RegisterStartupScript("aa", "<script>alert('login name already exists Please enter another login name');</script>");
textboxFirstName.Text = (String)Session["firstname"]; ;
textboxLastName.Text = (String)Session["lastname"];
textboxLoginName.Text = "";
textboxLoginName.Focus();
textboxLoginPassword.Text = (String)Session["loginpassword"];
textboxReEnterPassword.Text = (String)Session["reenterpassword"];
textboxEmailAddress.Text = (String)Session["emailaddress"];
DropDownListLoanOfficerType.Text = (String)Session["loanofficertype"];
textboxCompanyName.Text = (String)Session["companyname"];
textboxCompanyURL.Text = (String)Session["companyurl"];
DropDownListRegistrationPeriod.Text = (String)Session["registrationperiod"];
textboxRegistrationAmount.Text = (String)Session["RegistrationAmount"];
}
//Values Assigning to Registration Page Controls When Back Button is Click in CreditCardinfo Page
if (Session["page"] == "yes")
{
textboxFirstName.Text = (String)Session["firstname"]; ;
textboxLastName.Text = (String)Session["lastname"];
textboxLoginName.Text = (String)Session["loginname"];
//textboxLoginName.Focus();
textboxLoginPassword.Text = (String)Session["loginpassword"];
textboxReEnterPassword.Text = (String)Session["reenterpassword"];
textboxEmailAddress.Text = (String)Session["emailaddress"];
DropDownListLoanOfficerType.Text = (String)Session["loanofficertype"];
textboxCompanyName.Text = (String)Session["companyname"];
textboxCompanyURL.Text = (String)Session["companyurl"];
DropDownListRegistrationPeriod.Text = (String)Session["registrationperiod"];
textboxRegistrationAmount.Text = (String)Session["RegistrationAmount"];
}
}
}