"Io le auguro una buona notte."

Translation: I wish her a good night.

[ackworth]

Why Is the use of "le" meaning them incorrect in this sentence?

[dnovinc]

Because "le" = "to her" in this sentence is an indirect object pronoun ( they answer the question a chi? (to whom) / a che cosa? / (to what ).

"to them" = "gli" (in formal writing "loro" is preferred to the plural pronoun "gli" (to them.)

check this for more information http://www.cyberitalian.com/en/html/gra_prpr.html

[OUMEN]

something wrong : why (i wish them ) is wrong ???? (le) supposed to be (them) not (her) .... gli = him ..... la her