Newbie troop loading question

[PanzerKnacker]

Hi guys. First of all thanks for a fantastic game! The attention to detail in the OOBs is amazing.

Now a question- can units only load onto vehicles with the same platoon letter? For example, in the tutorial scenario unit E2>PzGren Grp can load onto vehicle E4 no probs. But when i try to load A0>Kommandeur onto vehicle E3 it doesnt work, even though in the game guide tutorial notes it says "and you can load the Kommandeur onto his Sdkfz 251/10".