Altirra 2.20 - piggyback cartridges

I'm trying to get Altirra to work with SpartaDOS X + ACTION! Language cart. Either of those work great on its own, but in combination they doesn't. I need to use Sparta DOS cart, because I have floppy image formatted in SDX format (contains some ACTION! code examples).

I have couple of other "DOS-es" (floppy-powered) that can read it, but they probably have not full support for SDX format or do something funny to cartridge memory as after compiling or running any of those files I get "altirra error" window where it does say that it encountered problem (ACTION! cart rom is fine, I've checked it by manually copying content of one of shorter demos via notepad - it ran fine).

But going back to topic, I can't seem to make SDX+ACT combo work.

Here what I'm doing:

- Loading demo disk ATR as D1 (file->Disk Drives)
- Then loading SDX cart rom (8Mbit one) via File -> Attach Cartridge...
- Then selecting File->Secondary cartridge->Attach and selecting ACTION! cart
- Then making cold reset (Shift+f5)

After entering CAR command, I am greeted with this:


Can anyone help me resolve issue? I'm using Altirra 2.20 and SDX 4.46 (8Mbit cart). For ACTION! version, I don't know - it is generic ACTION! rom contained in file #action.rom (17kb).