writer_1, reader_1 were not defined and initialized in the beginning of script.
VuGen missed recording it (a lot of reasons), you can ask your app Dev for help to define them or you can do it by yourself if you understand your application.
writer_1: Maybe SQL Writer or XML Writer...
reader_1: Maybe SQL Writer or XML Reader...
Open your project with Visual Sudio to debug is a good choice, VuGen doesn't have useful functionality like VS.