I did this two ways which both seemed to work:
ScriptManager.GetCurrent(Page).Scripts.Add(new ScriptReference("jcrop", null));
This one I think works because if you look at the two constructors to ScriptReference
the one-parameter constructor has its parameter named path
and in the two-param constructor they are name
and assembly
. So I think your problem is that it was expecting a full path and you were giving it just a name.
The other way I did it was:
ScriptManager.RegisterNamedClientScriptResource(Page, "jcrop");
Which also seemed to work just fine. I hope this helps!