Collision between alwaysvisiblecontrol and ClientScript.RegisterStartupScript

I use AlwaysVisibleControl in a page and show a result of data access in popup with ClientScript(or ScriptManager). RegisterStartupScript.

ScriptManager.RegisterStartupScript(this, this.GetType(), "error",
                            "<script language=javascript> alert('* Saved well.');</script>", true);

When popup window appears after postback, alwaysvisiblecontrol is on wrong location.

(Initial html coded place not the alwaysvisible targeted place)

After I click OK button of poput, alwaysvisiblecontrol locates at target place.

I want this popup locates target place before popup window popups up.

Could anyone give me an advice about this? Thanks in advance.