Android on Rock64 SD Problem

[ElBoluTony]

Hi, first of all, i wanna say that i'm quite happy with the Rock64, i've a 4GB, Rev 2 version, that is working like a LibreELEC Media Center 24/7, PulseAudio Server without (almost) a glitch.
I'm trying to install Android on a SD Card, so far i've tried on a number of Cards without success;

8GB Kingston Class 10
16GB Sandisk Ultra
32GB Sandisk Extreme (i own a Couple)

The images were the following; 

android-7.1-rock-64-rock64_atv-v0.3.13-r115-raw.img
rock64_20171204_stock_android_7.1.2_rooted_sdboot.img
rock64_20180623_stock_android_8.1_sdboot.img
ROCK64_20190621_stock_rooted_android_9.0_sdboot.img
ROCK64_dd_20190621_stock_rooted_android_9.0_sdboot-16GB.img

ROCK64_dd_20190621_stock_rooted_android_9.0_sdboot-32GB.img

Flashed in a number of ways, first the Pine64 Installer, then Etcher, the Rockchip SDTool, Win32DiskImager, DD on Linux. 
None of the combinations booted into Android. 

I know that this is a developer SBC, i also tried Armbian and Manjaro ARM flawlessly, so i find quite strange this behaviour.

The PSU is a 3A 5v, i can acccept that maybe this unit will never boot into Android, but if there is a tip, i'll take it. 
i don't own a eMMC memory, i'm from Argentina and they are quite difficult to get here. 

Thanks!

For non-DD firmware build, please use RK tool to program.

Thanks tllim, i've tried again without success. 
Looks like i'm outta luck with this particular project.
Nevertheless i'm gonna keep playing with Armbian and LibreELEC. 

Thanks again!