Convert SIB to S7

Everything points to the fact that sib to s7 conversion represents export between different versions of Sibelius music notation files, something that may not be always possible.

Especially in cases like these, when someone would try to export newer version (.sib) to older one. Export to some exchange format instead might be wiser option here, provided the old version of Sibelius did support that particular format.

If you have any issues with both files, or have problems with exporting Sibelius files, it would be perhaps best to contact their support.