@Parvez Welcome! What source are you using? If you are using Game Capture, then you need to select the game in the source. Here are the steps.
- Right-click the source & select 'Properties'/double-click the source.
- Select one of these methods: A) Click 'Launch SyphonInject' which will open the said app. Select your game in the list. or B) Check the 'Inject' box & select your game in the 'Application' drop-down list.
- Select your injected game in the 'Source'(not to be confused with the OBS sources) drop-down list.