ASP.net button onserverclick only works when onclick isn’t defined

protected void btnNext_Click(object sender, EventArgs e) { btnNext.InnerHtml = "CLICK"; } <button type="submit" runat="server" onserverclick="btnNext_Click" id="btnNext">Next &gt;</button> This works fine, but when I add an onclick event: <button type="submit" runat="server" onserverclick="btnNext_Click" onclick="return checkForm();" id="btnNext">Next &gt;</button> And in the head: <script type="text/javascript"> function checkForm() { if (document.getElementById("<%=lstChooseSpec.ClientID %>").value) { return true; } else { $.jGrowl("<strong>Warning!</strong><br />Please … Read more