Aborted (core dumped) in GUI-qt after pressing on start

My system is;

ubuntu 16.04
opencv 3.4.1
qt 5.10.1

```bash
--------------------------------------------
Background Subtraction Library v2.0.0
https://github.com/andrewssobral/bgslibrary
by:
Andrews Sobral (andrewssobral@gmail.com)
--------------------------------------------
Using OpenCV version 3.4.1
Selected algorithm: DPMean
Looking for: ./config/DPMean.xml
Openning: ./dataset/video.avi

(bgslibrary_gui:16740): GStreamer-CRITICAL **: gst_element_make_from_uri: assertion 'gst_uri_is_valid (uri)' failed
GStreamer: Error opening bin: no source element for URI "./dataset/video.avi"
Cannot open video file ./dataset/video.avi
Openning: /home/majid/bgslibrary/dataset/video.avi
capture_fps: 30
capture_length: 374
OK!
DPMean()
OpenCV(3.4.1) Error: Null pointer (Invalid pointer to file storage) in cvWriteInt, file /home/majid/opencv/modules/core/src/persistence_c.cpp, line 859
terminate called after throwing an instance of 'cv::Exception'
what(): OpenCV(3.4.1) /home/majid/opencv/modules/core/src/persistence_c.cpp:859: error: (-27) Invalid pointer to file storage in function cvWriteInt

Aborted (core dumped)
```