Set Image URL based on if condtion on ASPX page

As of now this code always works on my local and doesnt acts weird. But when we deploy on server even though if IsEnabled value is set to true it will load isfalse.gif and therafter few days it will start to load correct image based on IsEnabled value.

IsEnabled is an simple property defined in codebehind.

protected bool IsEnabled 
{
    get { return Utility.GetValue(); }
}

ASPX Page :

<asp:Image ID="imgWebcast" ImageUrl='<%#(IsEnabled) ? "../../images/istrue.gif" : "../../images/isfalse.gif" %>'  />

I looked at below areas and all looks good :

  1. Cache precompiled files are deleted prior to deployment
  2. Cached is cleared
  3. IIS is reset

I can easily set it in code behind and resolve the above , but i need to understand the approach i did above is valid or not. Is something i am doing wrong. Does it achievable from the above approach