Problema repo XMBC

Sono alcuni giorni che dopo aver installato la repo di XMBC: http://mirrors.xmbc.org/apt/ios/ sul mio iphone 4 ios 5.1.1 mi da il seguiente errore:

GPG error: http://mirrors.xmbc.org./ Release: The following signatures were invalid: NODATA 1 NODATA 2

Failed to fetch
http://mirrors.xmbc.org/atp/ios/.packages.bz2 Sub-
process /bin/bzip2 returned an error code (2)

Some index files failed to download. they have been ignored or old ones used instead

Cosa devo fare?
Grazie Mariet