Acronis does not like sofware or 'fake' raid setups (on-board raids). It's generally good (and so is ghost, among others) for hardware based raid's as those present the raid drive to the OS as a scsi volume. the software does not need to know anything really about it.

I use acronis here for backing up my areca's and LSI raids. (well the boot raid's, the main areca one is just a tar/bacula backup of the data to tape).