unable to record in stereo

Audacity 2.1.0
Windows 10

Hi everyone, sorry for my bad english, my name is Andrew and I’am trying to record a song using a fender stratocaster guitar, an external soundcard 7.1 (CSL) and audacity.
I connect the guitar to the soundcard with the original cable and a Jack-minijack reduction ( the original cable is a monocable) the reduction in stereo.
When i record i obtain a signal only in one channel (dx). If I play the song , listening it with phones i hear the music only in one side.
I have read all tutorials but i haven’t found a solution , how can i record in stereo ?
Ps: i connect directly the guitar to the soundcard (witch a cheap one), and the soundcard is connected to laptop with a usb cable.

Thank you everyone will try to help me ANdrea

To record “stereo” you need to have two signal sources, such as two microphones, or left and right outputs from a cassette player.

For single channel signals (such as one microphone or one guitar pickup), you need to set Audacity to record “1 channel (mono)” in the device toolbar. When you play it back, you should hear sound in both left and right headphones.