User contorol does not return values

Hi ,

I have a user control which has a drop down menu and a text box ... I have been  trying to get the values I select in the drop down menu and the text i type in  the text box in the parent form (WebForm1.aspx) . I have delclared  two property in the ascx page

                               public string zipcode
            {
                  get{return TextBox1.Text.ToString();}
                  
            }
            
            public  string SLocation
            {
                  get{return DropDownList1.SelectedValue.ToString(); }
                  
                  
            }
I zipcode is the value i would be reurning from the text box and Slocation would the value I would be returning frm the drop down menu.

In Webform1.aspx I have delcared

protected  projectNamespce.UserControlclass  c;

I have dragged and dropped the user control in the aspx page
I hve a button on the Webform1.aspx
 
When i run the project .... I get the user control wich contains the dropdown menu and the text box and a button which I added to the aspx page...

I select the dropdown and type some thning in the text box ... and on click on the button .... I have just written
private void Button1_Click(object sender, System.EventArgs e)
            {
             Response.Write(c.SLocation);
            Response.Write(c.zipcode);
            }

but i get an error message sayin ...object refrence not set .... I have no idea as to whats happening here ..

any help is greatly appreciated

ashwin