My cubase won't record the sound from midi tracks to an audio track


I am using Cubase Artist 9, to replace my original cubase LE8.
I am also using a Juno DI synthesizer.
I love a lot of the sounds from the synth. And I depend a lot on them, in addition to some plugin sounds I bought.

I used to play on the synth and record in cubase using midi tracks.
After doing adjustments like tuning velocity, copy and paste or moving the notes, I will open a new audio track and press “record” while I solo the midi track.
Then the sounds from my synth can be recorded to the audio track and after exporting–> audio mixdown–> i can include the sounds from my synth.

But after I have installed the new cubase artist 9, and when I press record, the midi track was still playing, but on the audio track, only a straight line appeared. There are no waveform and of cause I can not hear anything when I solo the audio track.

Since I depend a lot on the sounds from the synth, I really hope to find a solution to it. It always works fine like that in the past.
Now even I use the old cubase LE8 I can not perform this step either…

Please, I would be really thankful if anyone could help to figure out my problem!

Sounds like your VST Connections and / or track input connections are not set up correctly.