How to initialize a modem pppd deamon with wvdial?

I am in the proscess of writting an c++ application to menage a modem connection on my arm board. I would like to use the wvdial utility for this. Unfortunately I have a problem. When startng "wvdialconf" the modem is detected and the file "wvdial.conf" is initialized.

# sudo wvdialconf
Editing `/etc/wvdial.conf'.

Scanning your serial ports for a modem.

Modem Port Scan<*1>: S0 S1 S2 S3
ttyUSB0<*1>: ATQ0 V1 E1 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 Z -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK
ttyUSB0<*1>: Modem Identifier: ATI -- 332
ttyUSB0<*1>: Speed 4800: AT -- OK
ttyUSB0<*1>: Speed 9600: AT -- OK
ttyUSB0<*1>: Speed 19200: AT -- OK
ttyUSB0<*1>: Speed 38400: AT -- OK
ttyUSB0<*1>: Speed 57600: AT -- OK
ttyUSB0<*1>: Speed 115200: AT -- OK
ttyUSB0<*1>: Speed 230400: AT -- OK
ttyUSB0<*1>: Speed 460800: AT -- Speed 460800: AT -- Speed 460800: AT -- Max
speed is 230400; that should be safe.
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK

Found a modem on /dev/ttyUSB0.
Modem configuration written to /etc/wvdial.conf.
ttyUSB0<Info>: Speed 230400; init "ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0"

My "wvdial.conf" file:

[Dialer Defaults]
Init1 = ATZ
Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
Init3 = AT+CGDCONT=1,"IP","myapn"
Stupid Mode = 1
Modem Type = Analog Modem
ISDN = 0
New PPPD = yes
Phone = *99#
Modem = /dev/ttyUSB0
Username = " "
Password = " "
Baud = 230400

But when I try run "wvdial" or "wvdial -c" or "wvdial

# sudo wvdial
--> WvDial: Internet dialer version 1.61
--> Warning: section [Dialer Defaults] does not exist in wvdial.conf.
--> Cannot open /dev/modem: No such file or directory
--> Cannot open /dev/modem: No such file or directory
--> Cannot open /dev/modem: No such file or directory
# sudo wvdial -c
--> WvDial: Internet dialer version 1.61
--> Warning: section [Dialer Defaults] does not exist in wvdial.conf.
--> Initializing modem.
--> Sending: ATZ
--> Sending: ATQ0
--> Re-Sending: ATZ
--> Modem not responding.
# sudo wvdial /etc/wvdial.conf
--> WvDial: Internet dialer version 1.61
--> Warning: section [Dialer /etc/wvdial.conf] does not exist in wvdial.conf.
--> Cannot open /dev/modem: No such file or directory
--> Cannot open /dev/modem: No such file or directory
--> Cannot open /dev/modem: No such file or directory

Unfortunately I have no idea to. The configuration file exists but wvdial does not see it. I don't know if it matters but I don't have file "pap-secrets" and "chap-secrets" in the path "/etc/ppp/"