Error in WaterOrientationalRelaxation calculation

[saikat pal]

Dear all,
I am using the following script to calculate the WaterOrientationalRelaxation calculation. Here is the following script:
`import MDAnalysis
from MDAnalysis.analysis.waterdynamics import WaterOrientationalRelaxation as WOR

u = MDAnalysis.Universe("6L1W_nuc.psf", "cum_md1_1-image.dcd")
select = "byres name OH2 and sphzone 6.0 nucleic"
WOR_analysis = WOR(Universe, select, 0, 5000, 20)
WOR_analysis.run()
time = 0
#now we print the data ready to plot. The first two columns are WOR_OH vs t plot,
#the second two columns are WOR_HH vs t graph and the third two columns are WOR_dip vs t graph
for WOR_OH, WOR_HH, WOR_dip in WOR_analysis.timeseries:
    print("{time} {WOR_OH} {time} {WOR_HH} {time} {WOR_dip}".format(time=time, WOR_OH=WOR_OH, WOR_HH=WOR_HH,WOR_dip=WOR_dip))
    time += 1


#now, if we want, we can plot our data
plt.figure(1,figsize=(18, 6))

#WOR OH
plt.subplot(131)
plt.xlabel('time')
plt.ylabel('WOR')
plt.title('WOR OH')
plt.plot(range(0,time),[column[0] for column in WOR_analysis.timeseries])

#WOR HH
plt.subplot(132)
plt.xlabel('time')
plt.ylabel('WOR')
plt.title('WOR HH')
plt.plot(range(0,time),[column[1] for column in WOR_analysis.timeseries])

#WOR dip
plt.subplot(133)
plt.xlabel('time')
plt.ylabel('WOR')
plt.title('WOR dip')
plt.plot(range(0,time),[column[2] for column in WOR_analysis.timeseries])

plt.show()
`
However, I am getting the following error :
AttributeError                            Traceback (most recent call last)
/tmp/ipykernel_3280062/1319508095.py in <module>
      9 select = "byres name OH2 and sphzone 6.0 nucleic"
     10 WOR_analysis = WOR(Universe, select, 0, 5000, 20)
---> 11 WOR_analysis.run()
     12 time = 0
     13 #now we print the data ready to plot. The first two columns are WOR_OH vs t plot,

~/softwares/amber20_src/build/CMakeFiles/miniconda/install/envs/mdaenv/lib/python3.8/site-packages/MDAnalysis/analysis/waterdynamics.py in run(self, **kwargs)
    582         # later.
    583         if self.nproc == 1:
--> 584             selection_out = self._selection_serial(
    585                 self.universe, self.selection)
    586         else:

~/softwares/amber20_src/build/CMakeFiles/miniconda/install/envs/mdaenv/lib/python3.8/site-packages/MDAnalysis/analysis/waterdynamics.py in _selection_serial(self, universe, selection_str)
    567         selection = []
    568         for ts in ProgressBar(universe.trajectory, verbose=True,
--> 569                               total=universe.trajectory.n_frames):
    570             selection.append(universe.select_atoms(selection_str))
    571         return selection

AttributeError: 'property' object has no attribute 'n_frames'

Please help me out.