Why can't I access this Ext4 partition using FUSE?

I have installed FUSE for OS X. During installation I ticked the "compatibility layer" option. I have rebooted after installation. I have an external HDD with one NTFS partition and two Ext4 partitions. Operating systems are installed on the partitions. I am only able to mount the NTFS partition. The Ext4 partitions appear in Disk Utility, but nothing happens when I try to mount them. What can I do to access them?