GWT and Vaadin - variable is not a constructor stack

Question

I have a strange error that I cannot make heads or tails of. A snippet of the error is below:

(TypeError): $wnd.EGeoXml is not a constructor stack: $jsInit([object Object],[object Object],null)

The actual lines of code is in GWT and looks like this:

private native void jsInit(JavaScriptObject map, String kmlFile) /*-{
        var exml = new $wnd.EGeoXml("exml", map, kmlFile, {});
        [email protected]::ready(Lcom/google/gwt/core/client/JavaScriptObject;)(exml);
    }-*/;

This code actually works when running as its own GWT project but when using this code with Vaadin, I get the constructor stack error. I'm positive the constructor exists. What I do not understand is why GWT thinks it's not a constructor? Thanks in advance.