Place the rail on the funnel?

When I try to place a rail on a funnel in the Pocket Edition in Minecraft, only the funnel opens. What can I do?

Between the walking buttons there's another button in the middle: press, you have to press it twice

OK

You have to sneak while you want to place it. That means:
Press jump button twice

If a block can't be placed because a "special block" prevents it, there are several options:

Switch to "sneak", which prevents some blocks from being operated.
Put an auxiliary block next to it so that one clicks on to place the new block instead of the "special block".
Place the new block next to it and push it into place with a "piston" (piston?). All you need is a piston on which you put a button or lever.

At 3 you would place two more blocks next to the funnel, the rail on the first and the piston on the second. If you activate the piston at the push of a button, it pushes the rail onto the funnel. Then remove the auxiliary blocks and piston.

So sneak-click Shift key

Wrong version! 😂