Cannot set multiple phase transition depths in Latent heat subsection for Material model

Hello there,
I am currently using version 2.2.0 of ASPECT and am trying to include phase transitions in the model. When working with only one transition, everything works fine. But upon including two transition depths I keep getting error messages that the phase transition depths are not provided in the correct format, although I provided them as comma separated lists, just as ASPECT demands. See the code and error message below. Any help would be much appreciated. Thank you all in advance.

# Setup
# - with unstable initial conditions
# - simple material model

set Dimension = 2

set Start time                             = 0
set End time                               = 1e9
set Use years in output instead of seconds = true

set Output directory                       = NGP-phase-2layer

# Geometry definition
# Rectangular box of 3000 x 3000 km
subsection Geometry model
  set Model name = box
  subsection Box
    set X extent = 3000000
    set Y extent = 3000000

############### Boundary conditions

 # Set only tangential velocities at the boundaries (free slip)
subsection Boundary velocity model
  set Tangential velocity boundary indicators = 0,1,2,3
  set Prescribed velocity boundary indicators = 

# Set temperature at top to 1600 K and 4000 K at bottom
subsection Boundary temperature model
  # Fix temperatures at top and bottom
  set Fixed temperature boundary indicators   = 2,3
  set Model name = box
  subsection Box
    set Bottom temperature = 4000
    set Top temperature = 1600 

subsection Initial temperature model
  set Model name = function
  subsection Function
    set Variable names      = x,z
	  # Initial temperature is roughly adiabatic + a big hot blob at the bottom
    set Function expression = 3100 - z*0.5e-3 + if (x>1.5e6 & x<2.5e6 & z<1e6,500,0)

# Material properties
subsection Material model
  set Model name = latent heat

  subsection Latent heat
    set Thermal expansion coefficient = 4e-5
    set Viscosity                     = 1e22
    set Thermal conductivity = 4.7
    set Compressibility = 4e-12

    ## Add bogus phase transitions - this is nonsense!
    set Phase transition Clapeyron slopes = 2e6, -3e6
    set Phase transition temperatures = 1700, 2000
    set Phase transition depths = 500e3, 1500e3
    set Phase transition density jumps = 250, 400
    set Phase transition widths = 1000, 1000
    set Viscosity prefactors = 1.0, 1.0, 1.0
    set Corresponding phase for density jump = 0, 0

# Gravity is constant
subsection Gravity model
  set Model name = vertical
  subsection Vertical
    set Magnitude = 10.0

#without adiabatic heating and constant heating
subsection Heating model
  set List of model names = shear heating, latent heat

subsection Mesh refinement
  set Initial adaptive refinement        = 0 
  set Initial global refinement          = 5
  set Time steps between mesh refinement = 10
  set Strategy = temperature,density


subsection Postprocess

  set List of postprocessors = visualization

  subsection Visualization

    set Number of grouped files       = 0
    set Output format                 = vtu
    set Time between graphical output = 1e6
    set List of output variables      = density,heating
    set Interpolate output = true

The error message:

Exception 'ExcMessage ("The required format for property <" + property_name + "> was not found. Specify a comma separated " + "list of `<double>' or `<key1> : <double>|<double>|..., " + "<key2> : <double>|... , ... '.")' on rank 0 on processing: 

An error occurred in line <198> of file </home/ubuntu/aspect/source/> in function
    std::multimap<std::__cxx11::basic_string<char>, double> aspect::Utilities::{anonymous}::parse_string_to_map(const string&, const std::vector<std::__cxx11::basic_string<char> >&, const string&)
The violated condition was: 
Additional information: 
    The required format for property <Phase transition depths> was not found. Specify a comma separated list of `<double>' or `<key1> : <double>|<double>|..., <key2> : <double>|... , ... '.

Dear Dina,

ASPECT uses comma separated lists for different compositional fields. In your prm, you have only one compositional field, but several phase transitions, so you should instead use the second format suggested by the error message, i.e. <key1> : <double>|<double>|

You should replace <key1> with the word all or background (this tells ASPECT that you want to use this phase transition list for either all compositional fields, or just the background compositional field, which in your case is the same).

See, for example tests/latent_heat_viscosity.prm.

Best wishes,