Help with usb interface

[roobban]

Hello.
I just bought a usb interface. When i decode with my soundcard i get almost 100% success rate on channel 161.4375mhz but with interface i get at the best 20% success. I want to decode channel 149.1125mhz but the signal is pretty bad. I dont get any results with soundcard at channel 149.1125 but i hear pocsag message been sent in the scanner.
Can anyone help me?

Best regards
Robert

Edit: Its pocsag 1200 i want to decode

[Discriminator]

Do you use a discriminator output on your receiver?

[roobban]

Yes i do!