Standing on FFmpeg.Conversions.FromSnippet.AddAudio, not running or do anything

[dim0147]

Hi, I create Window Form GUI and when init Form 1 I run startTest which add audio to video and output to result.mp4, but when debug the program is waiting for await FFmpeg.Conversions.FromSnippet.AddAudio(videoDir, audioDir, outputDir); to be done but at this line I'm waiting around 1 hour and no response, I don't know it's encounter error or something wrong because it not respond anything (didn't throw an error or something), and I really sure can I add audio to this video only around few seconds (tested using ffmpeg command line) but when implementing in this it not do anything