XSD file imported into PI as external definition showing some nodes red in color

Hi Sap gurus.

I have imported a XSD file into PI Design as an External definition but some nodes (referring to other xsd's which were already imported into PI design ) are showing in Red color but the object is activated without any errors.

also the nodes are not referring to the respective xsd's (which were already imported into PI as external definition).

could any body help me in this ?

Regards.

Jagdish.