RNG schema is incorrect for a valid RNG schema in Oxygen

[JulieGiovacchini]

Hello, I use regularly Scholarly XML for TEI and never met this problem before : I try to valid my file with a RNG schema that is valid in Oxygen, and the association does not work in VSCode, the error message "RNG schema is incorrect" appears, with mention "could not parse schema".
The schema is valid in Oxygen validator, so it means that there is something that trigger Scholarly XML validation and that is not related to RNG syntax. Is there any internal constraint that could explain this behaviour ?

[angelozerr]

Could you share your schema and XML please.

[JulieGiovacchini]

schema_validation_truble.zip
hello, sorry I did'nt find your answer till today. Here are the files we have worked with in June.