They are not accepted as part of the Hebrew Bible because they were not composed in the Hebrew language. These are Jewish writings that were composed in Greek.You see Jews divide their sacred texts by different categories, and we also don't view "canonization" in the same light that Christians do. (In fact, the Scripture "canon" was invented by the Christian Gnostic heretic Marcion of Sinope, and even the word "canon" is Greek, not Hebrew.)
Thanks Caleb, pretty good information