Hello Ally,
Can you please confirm that system is allowing to do scheduling at what level in-spite of the Factory Calendar settings for Saturday and Sunday? Do confirm the assignments in OX10, OP03, OVLZ, OVXD and OVX5. Also, check 'Lead time in days' and 'Propose deliv. date' in VOV8. If this all doesn't work then how about defining Special Rule in SCAL?. Test the same in your DEV server after making Sat and Sun as an off-day and revert back with your findings. Thanks.