about java script validation

this is my java script code for validation.

function emptelephoneno() {
     var elem = document.getElementById('<%=txtfullname.ClientID%>');
     if (elem.value.length == 0) {
         elem.style.border = '1px solid red';
         document.getElementById('nameError').innerHTML = "Please Enter Your First Name";
         return false;
     }
     else {
         elem.style.border = '';
         document.getElementById('nameError').innerHTML = "";
     }
     return true;
 }
      function emptelephoneno1() {
      var elem1 = document.getElementById('<%=TextBox1.ClientID%>');
      if (elem1.value.length == 0) {
          elem1.style.border = '1px solid red';
          document.getElementById('Span1').innerHTML = "Please Enter Your First Name";
          return false;
      }
      else {
          elem1.style.border = '';
          document.getElementById('Span1').innerHTML = "";
      }

      return true;
  }
  </script>

this is my textbox where i want to use this code..

<div class="divRegistration">
   <div class="divleft">
   <label> full name :<span class="spanstar">*</span></label>
   </div>
   <div class="divright">
    <asp:TextBox ID="txtfullname" runat="server" MaxLength="30"></asp:TextBox>
    <span id="nameError" class="spanerror"></span>
   </div>
   </div>

   <div class="divRegistration">
   <div class="divleft">
   <label> full name :<span class="spanstar">*</span></label>
   </div>
   <div class="divright">
    <asp:TextBox ID="txtname" runat="server" MaxLength="30"></asp:TextBox>
    <span id="Span1" class="spanerror"></span>
   </div>
   </div>

   <asp:Button ID="btn" runat="server" text="submit" OnClientClick="return emptelephoneno();return emptelephoneno1();"
        onclick="btn_Click" />
   </div>
   </div>
   </div>

and i am using this code's on my aspx.cs page also like that

this.txtfullname.Attributes.Add("onblur", "javascript:emptelephoneno();");
       this.txtname.Attributes.Add("onblur", "javascript:emptelephoneno1();");

when i click the button first validation is working but second validation is not working so please help me out...

Tags: ASP.NET