DALI : How commissioning process takes place in DALI system?
Start with Command 145, Query Ballast, sent broadcast. If you get no response to this, there are a few possibilities.


the gear is not connected or does not have mains power
There is too much cable between the power supply/query end and the
gear, there is a 2V maximum volt drop specified
the gear has a broken transmit transistor, caused by the use of an
unlimited or too high a limit on the current limited supply. DALI
supplies must be limited to 250mA maximum.
the gear meets edition 2 of IEC62386-102 and is in an Operating Mode
other than Mode 0.
The receiver does not have its threshold voltage between the
specified limits.


Once you have fixed this, the command sequence to set a short address when you only have one gear on the bus is


Set the DTR to the required short address in the special format
(shifted left one place, least significant bit set to 1).
Read the DTR to check that it is correct.
Send Command 128 Store DTR as Short Address, twice within 100ms, using broadcast addressing.


For this command sequence when you only have one gear on the bus, you do not need to send the Initialise or Randomise command. Whilst it is possible to commission many gear this way, by connecting or powering up one at a time and assigning unique short addresses, it is not normally done this way because of the inconvienience of having to ensure only one gear is on the bus at any one time. Then the randomise method is used, with all the gear powered up at once. Note that with the randomise method, some commands such as Initialise have to be sent twice in 100ms, and that the Program Short Address command is only executed inside gear where the 24 bit search address matched its random address, so your command sequence is incorrect.

My experience with Meanwell gear is that this should work unless you have broken your unit or have field wiring problems.