Password-Box Not Showing Any Content?

I have a small websolution that needs the user to input a password. I have two input boxes

<input type="password" runat="server" id="m_txtPassword1"/>

If I set some chars to the Value-property of the control like this:

m_txtPassword1.Value="someChars";

The password box is rendered empty. No bullets are shown. If I look into the rendered html-source, also no value-tag has been rendered. If I change the type to

<input type="text" runat="server" id="m_txtPassword1"/>

the chars are shown. Is this by design? How can I disable this feature? I don't want to put a real password into the value-property, I only want to show the user that there is already a password set, and this is IMO done best with some 8 bullets in the input-control. But for this, I need the possibility to set the value-property of the control.

Update

For all, having the same problem: I have tried to declare <asp:textbox id="m_txtPassword1" runat="server" TextMode="Password" /> with the same result. Also m_txtPassword1.Attributes["value"]="someChars" has not helped.

As a workaround, I declared the password-boxes as plain html without the runat="server" and have set the value-property in markup (via two properties from the code-behind). Not nice but I really want to show the user that he has already entered a password.Another workaround would be to set the value through javascript on load.