installation problem macos

I am running macos 10.5.8 and trying to install version 1.2. When I launch the app it quits with the following errors:

Process: mscore [403]
Path: /Volumes/MuseScore-1.2/MuseScore.app/Contents/MacOS/mscore
Identifier: net.sourceforge.mscore
Version: ??? (???)
Code Type: X86 (Native)
Parent Process: launchd [111]

Interval Since Last Report: 1391057 sec
Crashes Since Last Report: 48
Per-App Interval Since Last Report: 0 sec
Per-App Crashes Since Last Report: 6

Date/Time: 2012-04-16 10:24:52.981 +0100
OS Version: Mac OS X 10.5.8 (9L30)
Report Version: 6
Anonymous UUID: 38228768-337A-4A0F-B339-4E37F216F3C9

Exception Type: EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000002, 0x0000000000000000
Crashed Thread: 0

Dyld Error Message:
unknown required load command 0x80000022
Don't know what that means. I have managed to get 1.1 installed.
Thx