USRP: Source to Sink

Is there any problem of connecting a usrp.source_c to an usrp.sink_c?
I reverted to try and simply connect the two in software when
something else I was trying was not working. When I start running my
script I see it attach to my subdevices (rfx1800_rx, lftx), but then
completes the script right away. I was thinking I may need some delay
between establishing the source and sinking it, but that didn’t seem
to help. Any suggestions

Thanks
Jeff

Attached is my file (messy) that I trimmed down and was working with.
It is really just usrp_siggen and usrp_oscope combined.