Index was out of range

Halloo....

I need your help badly :(

Please do help me to solve this error...
I got this error after i save the first record and navigate to the next record and then save.

Thanks Thanks....

"Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index"

Code:

---

private int _TaxCodeId;
    private TaxCode _TaxCode;
    protected void Page_Load(object sender, EventArgs e)
    {
        _TaxCodeId = AlwaysConvert.ToInt(Request.QueryString["TaxCodeId"]);
        _TaxCode  = TaxCodeDataSource.Load(_TaxCodeId);
        if (_TaxCode == null) Response.Redirect("TaxCodes.aspx");
        if (!Page.IsPostBack)
        {
            Caption.Text = string.Format(Caption.Text, _TaxCode.Name);
        }
    }

    protected bool IsLinked(object dataItem)
    {
        TaxRule rule = (TaxRule)dataItem;
        return (rule.TaxRuleTaxCodes.IndexOf(rule.TaxRuleId, _TaxCodeId) > -1);
    }

    protected void Linked_CheckChanged(object sender, EventArgs e)
    {
        CheckBox linked = (CheckBox)sender;
        int taxRuleId = AlwaysConvert.ToInt(linked.Text);
        TaxRule taxRule = TaxRuleDataSource.Load(taxRuleId);
        if (linked.Checked)
        {
            //ADD IF NOT FOUND
            if (taxRule.TaxRuleTaxCodes.IndexOf(taxRuleId, _TaxCodeId) < 0)
            {
                taxRule.TaxRuleTaxCodes.Add(new TaxRuleTaxCode(taxRuleId, _TaxCodeId));
                taxRule.Save();
            }
        }
        else
        {
            //DELETE IF FOUND
            int index = taxRule.TaxRuleTaxCodes.IndexOf(taxRuleId, _TaxCodeId);
            if (index > -1)
            {
                taxRule.TaxRuleTaxCodes.DeleteAt(index);
            }
        }
        TaxRuleGrid.DataBind();
    }

    protected void SaveButton_Click(object sender, EventArgs e)
    {
        _TaxCode.TaxRuleTaxCodes.DeleteAll();
        foreach (GridViewRow gvr in TaxRuleGrid.Rows)
        {
            CheckBox Linked = gvr.FindControl("Linked") as CheckBox;
            if (Linked.Checked)
            {
                int taxRuleId = (int)TaxRuleGrid.DataKeys[gvr.DataItemIndex].Value;
                _TaxCode.TaxRuleTaxCodes.Add(new TaxRuleTaxCode(taxRuleId, _TaxCodeId));
            }
        }
        _TaxCode.Save();
        SavedMessage.Visible = true;
        SavedMessage.Text = string.Format(SavedMessage.Text, LocaleHelper.LocalNow);
    }

---

"Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index"


You get this error message if you create an array like:

int[] x = new int [4];

then if i do x[2] = 5; // this is correct and will assign 5 to index number 1 of the array since an array starts from 0.

But if i do x[7]=5; // I will get the above error since the size of the array is less than index number 7, it does not exist.

The object name to be concerned in INDEX.

Please point out which line throws the exception in future, so we don't have to search through the entire code. I had a look at your code but it's not obvious where the issue is so you have to wait longer for a solution. You provided the error message, which is more than many people bother to do, but where the error occurred is always important too.