Transmission not clicking into gear

We changed the engine oil from the car, and realized later we drained the transmission fluid instead, hard to notice, as both plugs are next to each other. And the oil came out black. We have just put back 2.5L and it's still not going into gear.

Not sure what to do now, we are going to try put more ATF in, but not sure why it's still not clicking in.

Any help please as to why no gear is engaging?
We got the littlest pull but it cut out and went into neutral.