Why microSD not being able to have BartPE installed

I was kind of frustrated by the fact the all (actually two) of my microSD cards are failed to start with BartPE, a self-contain scale down version of windows bootup environment that allows you to bootup your machine under emergency. The brands of the microSD card i tried was Trendcent (a 1Gb card) and KingMax (a 512Mb card). And I used them on several SD card enclosures and card reader, and they all failed while the regular SD card succeed to boot BartPE with the same SD card thumb drive enclosure.

I spent a darn night to came up with the conclusion, and boy I was pissed.

So as of now I am pretty much give up on having the smallest thumbdrive that support Windows bootup with microSD. Darn. Oh well, I can always put windows 98 with DOS support of them.