Rabbi Berel Wein writes:
Nevertheless, there is a biblical injunction "not to turn to the dead [for help]." Praying to the dead was seen in the Torah as being an idolatrous practice. Jewish law books stress that one should never pray to the dead but rather one should gain inspiration by recalling their righteousness and thereby pray to the Lord more intensely and effectively.…
The Ari (Rabbi Yitzhak Luria, famed 16th-century kabbalist) stated that one should not visit cemeteries at all, except when it is tragically incumbent [to bury the dead] to be present there.
Funny, isn't Chabad theology based on praying to and communicating with the dead? Didn't the Rebbe spend hours every week in a cemetery doing so? Could it be that Chabad is wrong? That the Rebbe was wrong?
You can read it all here.