What is the funtion of tape out, tel, pre amp out , power out, vox, alc... & what is aux dfrs???

You can use any spare connection, such as tape, aux, CD. However you will have to purchase a magnetic cartridge pre-amp, otherwise you will only hear a faint sound from the deck.
Only connect the deck to the pre-amp. If you are short on connections, then you can get a switching box, which will allow several devices to be connect to one socket on you amp.

If the amp has no dedicated plugs for a record player to be attached to it, it will not have a pre-amp for the magnetic cartridge built into it. What you need to get is a magnetic cartridge pre-amp. This fits between the deck and main amp. The fact that you can sound now shows that the cartridge is good and the amp is good. It just needs a pre-amp to boost the signal,

Has the Denon got a magnetic cartridge pre-amp built in? A good indication that it has will be if has a dedicated socket for a record deck. Connecting it to a tape or aux will only work if you purchase a separate Magnetic Cartridge pre-amp.

If it has socket for a magnetic cartridge. Yes. If not then you would need to get a magnetic cartridge pre-amp. This can then be connected to an aux or tape socket on the Bogen.

You are doing nothing wrong at all. It's just that as you say it has no phono input. Which means the sockets you have will NOT amplify the signal. So you need to buy a magnetic cartridge pre-amp and once connected to the aux the weak signal will be at the normal level.

Record players require a PHONO input on an amp.
Most amps no longer have this, so you will need to source out a pre-amp for the record player, and then you can plug the record player into the pre-amp and then hook the pre-amp into a tape, DVD or AUX input.

If your preamp has a Tape Monitor loop:

Eq Pre or Line Out to Preamp Tape In
EQ Pre or Line In to Preamp Tape Out

CD to Aux on the preamp

Engage the Tape Monitor to place the EQ between any source attached the the preamp (including the CD) and whatever follows it (an amp??).

Is the aux imput for tape or cd only? Or is it a dedicated phono imput?
If it is for tape or CD only it won't work has the cartridge from the deck needs a magnetic pre-amp.
If the amp doesn't have a phono imput you can get a pre-amp for cartridges from your local electrical shop. This will plug into your deck and then into the socket of the amp.
If the aux on your amp is a phono socket, assuming the record deck is working, then the pre-amp (inside your amp) for the cartridge has failed. It generally is located near the imput socket, chances are it will be single IC. It's a fair bet the IC will have failed, they tend to be static sensitive types prone to fail at the drop of a hat!

Please let me know how your turntable is connected to the music system. I mean, to which input ? (Tape/Aux/Phono/VCR/CD) ?

IF your amp has a phono input, you need nothing special. If all you have is aux inputs or an extra tape input, you need a phono pre-amp that will increase the signal level to that of a cd player or tape player. These are simple pre-amps that cost around $20.
Dan