Excel renamed (and extended) BETADIST and BETAINV to BETA.DIST and BETA.INV. Currently, Libreoffice does not yet support these renamed functions.
See https://bugs.freedesktop.org/attachment.cgi?id=88108 of meta bug 70798 for test case.
Winfried Donkers committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/core/commit/?id=6d2f42199c2a9b48c9e19d7ae087f5452bfbd401 fdo#71008 add Excel 2010 functions BETA.DEST and BETA.INV The patch should be included in the daily builds available at http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: http://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.