Strange Happenings with asp:textbox

I need to create a returns form as an independent page, we'll call it returnsForm.aspx.
I have created the page in Dreamweaver and included a simple asp form with asp:textboxes.
I want the adddress box to be multiline. see code sample.
  <asp:TextBox
    ID="txtAddress"
    TextMode="MultiLine"
    Columns="30"
    Rows="5"
    Runat="server" TabIndex="2"
  />

When I upload the finished page to the NOPCommerce server the address box looks like a single line.
When I upload the page to a regular asp.net server the textbox displays as multiline.
Anybody know why this happens?