Questions about transport vehicles

[Publilius]

Sorry for any confusion. A specific example is, I bought a veteran infantry platoon and the vehicles needed to carry them. I assigned the vehicles to the infantry company. I then placed each infantry company over the trucks and pushed the L button. Nothing happens. It only seems to work if they are in the same platoon.
I will verify again tomorrow. I thought the icon even says "Load all vehicles onto platoon transport" or something to that effect during deployment.

Thanks for the responses. I assumed I had to be doing something wrong.