VHS C Audio isnt working for my transfers

[jtcavataio]

Hi, new to the group so thank you for the add. I am finally trying to transfer all our old VHS C tapes using a Diamond VC500 and things are going pretty well. I am using the VCR for regular vhs tapes, and the camera for my 8mm, but my VHS -C I have to rely on the adapter cartridge in the VHS. However, when I do this, there is no audio. Has anyone ever had this experience. The audio is fine with the other formats - can the adapter be impacting the audio -the video is playing just fine.