Image OnClick not firing but Button Event is - asp.net

Question

I have the html & Code below.
When the user hits the page first I want them to be able to select their language by clicking on a Flag icon (before or after signing in). The event should fire and the language choice will be set. They then should be able to carry on logging into the site (if not already logged in) and performing whatever business they need.
My problem is, however, whenever I click on any flag icon the login and/or password box error message is displayed (if the textbox is empty) even thought the Button Click is not fired.
Can anyone please give me a pointer on where I am going wrong as I am obviously missing something (probably the obvious).
Many thanks in advance for any assistance offered
Regards
Iain
<form id="form1"
runat="server">
<div style="position: absolute; right : 0px; right : 5%;"> <!-- The Language Icons -->
<asp:ImageButton id = "imgbEnglish"
runat = "server"
onserverclick = "imgbEnglish_Click"
ImageUrl = "~/images/Union Jack.jpg"
Width = "20px"
ToolTip = "English"
visible = "true"/>
..........
..........
..............................................
There are 9 image icons of the same definition
..............................................
..........
..........
</div> <!-- The Language Icons -->
<table align="center">
<tr>
<td colspan="2" height="200px"></td>
</tr>
<tr>
<td>
</td>
<td>
<b>
<asp:Label ID = "lblLoginBoxHeader"
runat = "server"
text = "Sign In">
</asp:Label>
</b>
</td>
</tr>
<tr>
<td>
<asp:Label ID = "lblUsername"
runat = "server"
text = "User Name">
</asp:Label>
</td>
<td>
<asp:TextBox ID="txtUserName"
runat="server"/>
<asp:RequiredFieldValidator ID="rfvUser"
ErrorMessage="Please enter a Username"
ControlToValidate="txtUserName"
runat="server" />
</td>
</tr>
<tr>
<td>
<asp:Label ID = "lblPassword"
runat = "server"
text = "Password">
</asp:Label>
</td>
<td>
<asp:TextBox ID="txtPWD"
runat="server"
TextMode="Password"/>
<asp:RequiredFieldValidator ID="rfvPWD"
runat="server"
ControlToValidate="txtPWD"
ErrorMessage="Please enter a Password"/>
</td>
</tr>
<tr>
<td>
</td>
<td>
<asp:Button ID="btnSubmit"
runat="server"
Text="Submit"
onclick="btnSubmit_Click" />
</td>
</tr>
<tr>
<td>
</td>
<td>
<asp:Label ID = "lblSignedIn"
runat = "server"
text = "">
</asp:Label>
</td>
</tr>
</table>
// The code behind is
protected void Page_Load ( object sender, EventArgs e )
{
if (!IsPostBack)
{
getTheLanguage();
lblSignedIn.Text = lblSignedIn + "<br />" + "Is Postback";
}
else
{
lblSignedIn.Text = lblSignedIn + "<br />" + "Is Postback";
}
}
protected void imgbEnglish_Click ( object sender, ImageClickEventArgs e )
{
Session["Language"] = "English";
lblCurrentLanguage.Text = "English";
}
protected void btnSubmit_Click(object sender, EventArgs e)
{
OleDbConnection con = new OleDbConnection(odbcString);
OleDbCommand cmd = new OleDbCommand();
string sqlString = "SELECT UPPER(VENCODE), UPPER(PASSWORD), COMPANY, QUALSITE, VENDSITE, CUSTSITE " +
"FROM QUALITY.USERLIST " +
"WHERE VENCODE = '" + txtUserName.Text.ToUpper() + "' AND " +
"PASSWORD = '" + txtPWD.Text.ToUpper() + "' " +
"ORDER BY VENCODE";
con.Open();
cmd.Connection = con;
cmd.CommandType = CommandType.Text;
cmd.CommandText = sqlString;
try
{
OleDbDataReader dsSite = cmd.ExecuteReader();
if (dsSite.HasRows)
{
lblSignedIn.Text = lblSignedIn + "<br />" + "Signed In";
}
else
{
lblSignedIn.Text = lblSignedIn + "<br />" + "Sign In Failed";
}
}
catch
{
}
con.Close();
}

Answer 1

Set
CausesValidation="false"
...
<asp:ImageButton id = "imgbEnglish"
runat = "server"
onserverclick = "imgbEnglish_Click"
ImageUrl = "~/images/Union Jack.jpg"
Width = "20px"
CausesValidation="false"
ToolTip = "English"
visible = "true"/>