Openwebrx and direct sampling mode crash

Hi my friends I'w got a problem wen install direct sampling mode. When install openwebrx everything is ok up and running. The problem is when I install the direct sampling mode (Have install 3 other and no problem). This is the first Ubuntu 18.04. I copy the log here but it is only from startup script. [openwebrx-main] Configuration script not specified. I will use: "config_webrx.py" [openwebrx-main] nmux_bufsize = 602112, nmux_bufcnt = 84 [openwebrx-main] Started rtl_thread: rtl_sdr -s 2400000 -f 144250000 -p 0 -g 5 -| nmux --bufsize 602112 --bufcnt 84 --port 4951 --address 127.0.0.1 [openwebrx-main] Waiting for I/Q server to start... rtl_sdr: symbol lookup error: rtl_sdr: undefined symbol: rtlsdr_set_dithering nmux: listening on 127.0.0.1:4951 nmux: (main thread/for) end input stream, exiting. Lars SM6HOC