No sound on 3CX softphone when second line is opened

[newportri]

I am testing out using multiple lines on my 3CX softphone with two cell phones, but I am having some sound problems. I make the first call from a cell phone to my 3CX phone, and I have sound both ways. However, when I call from a second cell phone on put the first call on hold, I don't get any speaker sound on the 3CX softphone. The 3CX microphone works and I can hear that in both cell phones when I switch between the two lines they are on. Once I disconnect one line, I get the speaker sound back on the 3CX softphone..
I am using the Primary Sound Capture driver for both the microphone and speaker on the 3CX softphone.
Any suggestions to what I should do to get this to work?
Thanks