System.ApplicationException: Invalid Theme at Wisej.Core.ClientTheme.GetInstance(String name)

When I load a form I get this error. how can I fix it?

in web.config is all set correctly:

<add key=”Wisej.DefaultTheme” value=”Blue-1″/>

System.ApplicationException: Invalid Theme    at Wisej.Core.ClientTheme.GetInstance(String name)    at Wisej.Base.ApplicationBase.get_Theme()    at Wisej.Base.Extensions.GetTheme(IComponent component)    at Wisej.Web.Form.SizeFromClientSize(Size clientSize)    at Wisej.Base.ControlBase.SetClientSizeCore(Int32 width, Int32 height)    at Wisej.Base.ControlBase.set_ClientSize(Size value)    at Wisej.Web.Form..ctor()    at …

thx