namespace CS_ASP_025
{
public partial class Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if(!Page.IsPostBack)
{
ViewState.Add("MyValue", "");
}
}

protected void addButton_Click(object sender, EventArgs e)
{
if (firstCheckBox.Checked &&
secondCheckBox.Checked &&
thirdCheckBox.Checked)
{
resultLabel.Text = "They're all checked!";
}

else
{
// I set up NOW the ViewState to nothing, which is what I want to get in case that the if statement does not apply:
ViewState["MyValue"] = "";
// but I need a string to pass to the label so:
string emptySolution = ViewState["MyValue"].ToString();
resultLabel.Text = emptySolution;
}
}
}
}