that’s it.
I finally solved it. the following code works well for me. if anyone else has a camera that is not UVC support, (GENICAM in my case), he/she can install aravissrc and use it instead of v4l2src. by opening up a command prompt in the directory of yolo and entering the following code, the whole setup can work using the following code:
gst-launch-1.0 -e --gst-plugin-path=/usr/local/lib/ aravissrc camera-name="U3V-00D24866386" ! nvvideoconvert ! "video/x-raw(memory:NVMM),width=(int)1280,height=(int)720,format=NV12" ! m.sink_0 nvstreammux name=m batch-size=1 width=1280 height=720 ! nvinfer config-file-path= /opt/nvidia/deepstream/deepstream-4.0/sources/yololight_car_test_jelo_panjereh_plate_both_backup/config_infer_primary_yoloV2_tiny.txt batch-size=1 unique-id=1 infer-on-class-ids=1 ! nvinfer config-file-path=/opt/nvidia/deepstream/deepstream-4.0/sources/yololight_car_test_jelo_panjereh_plate_both_backup/config_infer_primary_yoloV2_tiny.txt batch-size=1 unique-id=2 infer-on-gie-id=1 ! nvmultistreamtiler rows=1 columns=1 width=1280 height=720 ! nvvideoconvert ! nvdsosd ! nvegltransform ! nveglglessink sync=false