Problem on plotting ppsd of a wave

Hii, i want to compute the ppsd of a waveform.I write the code after following obspy documentations.

My code
`
import matplotlib.pyplot as plt
plt.style.use(“bmh”)
plt.rcParams[‘figure.figsize’] = 10, 6

from obspy import read, read_inventory

st = read(“1607.QHD”)
inv = read_inventory("/home/dk/Downloads/stationxml-seed-converter-master/dataless.G.HYB.seed")

print(st)
print(inv)
inv.plot(projection=“ortho”);

from obspy.signal import PPSD

tr = st[0]
ppsd = PPSD(stats=tr.stats, metadata=inv)

ppsd.add(tr)
ppsd.plot()
However, i get error Exception: No data accumulated` in ppsd.plot() step.As i am new to obspy i am unable to find out where error raise.Please help experts.Thanks in advance.

seems I replied to this already in gitter. The issue was a combo of a non-standard seed ID waveform + a too long ppsd_duration value.