Div Visibility set to property problem

 In my user control I have a div (it's not inside a container like a repeter for example):
<div visible="<%#ShowMessage %>" runat="server" >
The Item has been successfully added!
</div> In the code-behind of my user control, I have the property setup like this:
public bool ShowMessage
{
get{ return this.showMessage;}
set{ this.showMessage = value;}
}I set the property ...