Python actionDecl error

I’m trying to develop an actionDecl simple metric to compute euclidean distance between timeseries,when I try to run the evaluation the system gives me this error:

{
  "id" : "6339.9926",
  "key" : "c3.love.typesys.obj.pipe.ser.JsonObjValueIterator_parseError",
  "cause" : {
    "template" : "Unexpected end-of-input in FIELD_NAME\n at [Source: java.io.InputStreamReader@5f686f7a; line: 1, column: 23]"
  },
  "template" : "Parsing failed!",
  "parameters" : [ "com.fasterxml.jackson.core.JsonParseException: Unexpected end-of-input in FIELD_NAME\n at [Source: java.io.InputStreamReader@5f686f7a; line: 1, column: 23]" ],
  "codes" : [ "ParsingFailed" ]
}

Below the last part of code:
dp=zDistanceProfile(tsProfile,ts)
ts = timeseries.TimeSeries(start,‘MONTH’,[dp],[‘DistanceProfile’])
return ts

Which could be the cause of the error ?