That thing is top and when it does not work it is either broken or how often connected an incorrect antenna.

Have it in my 2002s Mondeo in conjunction with a Kenwood DDX 4025 DAB installed and the combination works perfectly.
The original antenna I had some time ago replaced by a Hirschmann, because I had problems with my old receiver (FM only) Kenwood DDX 4028 BT), but the reception was below average. Also, the test basis swap to another bauähnliches Kenwood DDX 3028 brought no improvement.

Then changed the radio and installed due to some postings this splitter. Additionally the Antennstab Hirschmann at 38cm shortened (optimal length for DAB) and the antenna placed almost vertically. The FM reception is better than ever, the actual very good K3i Tuner Kenwood is now working exactly as it should. Because where previously SWR 3 went down almost in the noise at once very good reception and now on the holiday trip to Croatia completely by Austria through all the time without any problems Ö3 received. Also in Slovenia and Croatia (where I had previously strive every few kilometers the channel scan) time of stable reception.
On a good DAB reception: SWR 3 from home over the Swabian Alb, and continue along the A8 to Augsburg behind, from there then Bayern 3 to about 20-30km to the Austrian border. In Italy, then again almost all the way to Slovenia DAB reception and even on the island of Cres in Croatia were often Italian channels can be received via DAB. Thus, the frag also amplifies the FM signal, I have solved my FM reception problem that Kenwood is many current devices probably not designed as the receiver side as sensitive as the radio earlier, probably because very few cars still have a reasonable rod antenna and therefore of House needs to be strongly reinforced everything.
If the splinter in someone does not function properly, it is either defective or improperly connected the antenna used is not suitable. One can assume that all factory short rod antennas (those things which so to are about 30cm long) to a built-in Antennfuß amplifiers have (which would then double amplifies the signal and which would then lead receiving portion to oversteer FM) and the built-in amplifier then usually also has filters which specifically the FM band and possibly still MW and LW passing, but it is no longer in the higher frequency range is moved DAB band. So you would have it almost absolutely no on VHF an excessively high level and on DAB. The reception would be worse than very bad before and DAB in the case of FM.