i have problems with vhf channels (in particular 186 and 194,5 Mhz, 7Mhz BW, Horiz)
You did not say which transponder list you are using, so I assume that you use "DVB-T Europe" (4000.ini) or "DVB-T Berlin" (4002.ini). The two frequencies you mention are not in these lists, so you should edit one of them manually. You can either delete two frequencies you are not using and replace these entries with the two new frequencies, or you can add your new frequecies to the list. In this case you must also edit the line numbers, and the entry "0=60" must be replaced by "0=62".
And you probably know that DVBDream can only scan a transponder at one bandwidth at a time. To get all DVB-T channels you have to add two transponders (e.g. DVB-T Europe at 8Mhz plus DVB-T Berlin at 7Mhz). Then you have to do two separate scans for each of the transponders.