Multiple generations are not booting?

[mprowe]

Software
XBian version: Not shown on 2015.04.04 (System | Summary)
XBMC/Kodi version: 14.2 (April 30 2015)
Overclock settings: default

Hardware
Device type and model Raspberry Pi Model B 512 MB
Power supply rating: 2.4A
SD card size and make/type: Various
Network (Ethernet or wireless): Both/Either
Connected devices TV

Log files
Link to logfile(s): None

Problem description:
Using the XBian Installer (V.1.21, the only generation that will boot is 2015.04.04? All others (2015.03.07, x.04.11, x.04.18 & x.04.25) will not boot

How to reproduce:
Use installer to create SD card with image 2015.04.04 and test. It boots and to all intent and purpose is working.
Using the exact same resources (Pi, installer, SD card) repeat with later images. Pi will not boot. No green SD activity LED seen at all!





Regards, Martin