8.1 Added Bus Rule and then Lost ability to build Lead Interface

[RichEaton]

I added a business rule to the Lead Entity, this is just the shell no code associated to it yet. I then tried to build interfaces and it blows up with the following error:

ERROR - <log4net.Error>Exception rendering object type [System.CodeDom.Compiler.CompilerError]<stackTrace>System.NullReferenceException: Object reference not set to an instance of an object.
at System.CodeDom.Compiler.CompilerError.ToString()
at log4net.ObjectRenderer.DefaultRenderer.RenderObject(RendererMap rendererMap, Object obj, TextWriter writer)
at log4net.ObjectRenderer.RendererMap.FindAndRender(Object obj, TextWriter writer)</stackTrace></log4net.Error>

Can someone point me to how I can find out WHAT is generating this error ?

I have even deleted the rule, tried to remove a property and add a property all in attempts to regenerate the Lead Interface. I have cleaned Build, and assembly folders, rebooted. 

any ideas are apprciated.

[ChrisGrant]

Have you tried clearing out your build path?

[RichEaton]

Yes multiple times, even deleted the entire site in case

[RichEaton · Accepted solution]

Fixed the build search path and then the isue corrected itself..??