Error - ShowPopup is not defined

In below code i am getting error

ShowMessage("Success", "Record Saved Successfully", "Success");

public void ShowMessage(String Title, String Text, String Type)
{
    Text = Text.Replace("'", "").Replace("/", " ").Replace(";", " ").Replace(":", " ").Replace(",", " ");
    Text = System.Text.RegularExpressions.Regex.Replace(Text, @"\t|\n|\r", " ");
    if (Common.CommonFunction.IE(Request.Browser.Browser))
    {
        Common.MessageBox.Show(Text);
    }
    else
    {
        ClientScript.RegisterStartupScript(this.GetType(), "Popup", "ShowPopUp('" + Title + "', '" + Text + "','" + Type + "');", true);
    }
}

private void ShowPopUp()
{
    System.Text.StringBuilder sb = new System.Text.StringBuilder();
    sb.Append(@"");

    ClientScript.RegisterStartupScript(this.GetType(), "JSScript", sb.ToString());
}

Thanks

The error you're encountering (ShowPopup is not defined) suggests that the JavaScript function ShowPopup is either missing or not defined in the client-side code and not sure about this method "private void ShowPopUp()" ?

Steps to fix the issue

1) Correct the JavaScript Funcation Name to "ShowPopUp"

public void ShowMessage(String Title, String Text, String Type)
{
    Text = Text.Replace("'", "").Replace("/", " ").Replace(";", " ").Replace(":", " ").Replace(",", " ");
    Text = System.Text.RegularExpressions.Regex.Replace(Text, @"\t|\n|\r", " ");
    if (Common.CommonFunction.IE(Request.Browser.Browser))
    {
        Common.MessageBox.Show(Text);
    }
    else
    {
        ClientScript.RegisterStartupScript(this.GetType(), "Popup", "ShowPopup('" + Title + "', '" + Text + "','" + Type + "');", true);
    }
}

2.Ensure that Request.Browser.Browser is returning a valid browser string.