probe analog/digital signals in AMS irun

I'm running into troubles when probing analog signals when doing AMS
irun simulation. The testbench is setup as SPICE top with some digital
subckt replaced by HDL specified in amsd{} block inside ams control
file.
I'm probing signals inside probe.tcl file. However, I'm not able to
probe any signals inside analog domain.

It reports error like as below:

# Successful create probes for digital signals
ncsim> probe -create -database waves {xcounter.*}
Created probe 3

# Fail to create probes for analog signals inside xpll_top
ncsim> probe -create -database waves xpll_top.*
ncsim: *E,PNOOBJ: Path element could not be found: xpll_top.