reftex-view-crossref seems not to work for external documents

[Uwe Brauer]

Hi 

according to the documentation 
,----
| reftex-view-crossref is an autoloaded interactive compiled Lisp
| function in ‘reftex-dcr.el’.
| 
| (reftex-view-crossref &optional ARG AUTO-HOW FAIL-QUIETLY)
| 
| View cross reference of macro at point.
| 
| Point must be on the KEY argument.  When at a ‘\ref’ macro, show
| corresponding ‘\label’ definition, also in external
| documents (‘xr’).  When on a label, show a locations where KEY is
| referenced.  Subsequent calls find additional locations.  When on
| a ‘\cite’, show the associated ‘\bibitem’ macro or the BibTeX
| database entry.  When on a ‘\bibitem’, show a ‘\cite’ macro
| which uses this KEY.  When on an ‘\index’, show other locations
| marked by the same index entry.
`----

I attach two files, using the externaldocument command.

When I run the reftex-view-crossref I obtain the following error 


,----
| Debugger entered--Lisp error: (error "ref: Label E:EULERPOISSON not found")
|   signal(error ("ref: Label E:EULERPOISSON not found"))
|   error("ref: Label %s not found" "E:EULERPOISSON")
|   reftex-view-cr-ref((4) "E:EULERPOISSON" nil)
|   reftex-view-crossref((4))
|   funcall-interactively(reftex-view-crossref (4))
|   call-interactively(reftex-view-crossref nil nil)
|   command-execute(reftex-view-crossref)
`----

Any idea what is the problem?

Regards

Uwe Brauer 

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I support the ban of Russia from SWIFT.
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file1.tex
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main.tex
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