Stack of time-spatial maps is not read by readmap method

I am new in PCRaster, so I made a primitive model to test the functionality. I need to read input from precipitation data maps for each day. My code is:

class Model(DynamicModel): 
    def __init__(self):
        DynamicModel.__init__(self)
        setclone(src.RasterYSize,src.RasterXSize,src.GetGeoTransform()[1],src.GetGeoTransform()[0],src.GetGeoTransform()[3])
    def initial(self):
        self.dem=self.readmap('dem')
        self.snowmaxTss=TimeoutputTimeseries("snowmax", self, None, noHeader=False)
    def dynamic(self):
        self.snow=self.readmap('/snowdata/snow')
        maxsnow=max(self.snow)
        self.snowmaxTss.sample(maxsnow)
myModel=Model()
dynModel = DynamicFramework(myModel, lastTimeStep=16, firstTimestep=1)
dynModel.run()

My snow maps stack is correct and corresponds to setclone. But I get an error:

RuntimeError                              Traceback (most recent call last)
<ipython-input-188-c7810b190e43> in <module>
     14 myModel=Model()
     15 dynModel = DynamicFramework(myModel, lastTimeStep=16, firstTimestep=1)
---> 16 dynModel.run()

/opt/conda/lib/python3.7/site-packages/pcraster/framework/dynamicFramework.py in run(self)
     63       self._runInitial()
     64 
---> 65     self._runDynamic()
     66 
     67     # Only execute this section while running filter frameworks.

/opt/conda/lib/python3.7/site-packages/pcraster/framework/frameworkBase.py in _runDynamic(self)
    369         self._incrementIndentLevel()
    370         self._traceIn("dynamic")
--> 371         self._userModel().dynamic()
    372         self._traceOut("dynamic")
    373         self._decrementIndentLevel()

<ipython-input-188-c7810b190e43> in dynamic(self)
      9         self.snowmaxTss=TimeoutputTimeseries("snowmax", self, None, noHeader=False)
     10     def dynamic(self):
---> 11         self.snow=self.readmap('/snowdata/snow')
     12         maxsnow=max(self.snow)
     13         self.snowmaxTss.sample(maxsnow)

/opt/conda/lib/python3.7/site-packages/pcraster/framework/dynamicPCRasterBase.py in readmap(self, name, style)
     78       `style` argument is not used.
     79     """
---> 80     return self._readmapNew(name)
     81 
     82   def _setNrTimeSteps(self,

/opt/conda/lib/python3.7/site-packages/pcraster/framework/frameworkBase.py in __call__(self, *args, **kwargs)
     35         if obj:
     36             attr = getattr(obj, self.callback_attr)
---> 37             result = attr(*args, **kwargs)
     38         else:
     39             result = self.default_callback(*args, **kwargs)

/opt/conda/lib/python3.7/site-packages/pcraster/framework/frameworkBase.py in _readmapNew(self, name, style)
    564     assert path is not ""
    565     import pcraster
--> 566     return pcraster.readmap(path)
    567 
    568   def _assertAndThrow(self,

RuntimeError: Raster /snowdata/snow0000.001: can not be opened

I tried different formats of file names: 0000.001, 0000.001.map etc – but result is the same. What’s the problem with my code? I know, that readmap() method must read stacks by time.
Is an xml file read when reading a map file? I convert from nc layers to map by GDAL and my xml files may contain odd information from the whole nc file.