Issues Running BEAST2

[Jessica Velez]

Help! I'm a student at UT Knoxville who is very new to bioinformatics, trying to teach myself how to use BEAST for some ddRAD data analysis. I have installed SNAPP and the Model Selection packages in BEAUTI. I have generated the included file from BEAUTI, but when I load this into BEAST for processing, I receive this error: 

Error 110 parsing the xml input file

validate and intialize error: Input 'tree' must be specified.

Error detected about here:

  <beast>

      <run spec='beast.inference.PathSampler'>

          <mcmc id='mcmc' spec='MCMC'>

              <distribution id='posterior' spec='util.CompoundDistribution'>

                  <distribution id='prior' spec='util.CompoundDistribution'>

                      <distribution id='Pop_1.prior' spec='beast.math.distributions.MRCAPrior'>

java.lang.IllegalArgumentException: Input 'tree' must be specified.

at beast.core.Input.validate(Unknown Source)

at beast.core.BEASTInterface.validateInputs(Unknown Source)

at beast.util.XMLParser.createObject(Unknown Source)

at beast.util.XMLParser.parseInputs(Unknown Source)

at beast.util.XMLParser.createObject(Unknown Source)

at beast.util.XMLParser.parseInputs(Unknown Source)

at beast.util.XMLParser.createObject(Unknown Source)

at beast.util.XMLParser.parseInputs(Unknown Source)

at beast.util.XMLParser.createObject(Unknown Source)

at beast.util.XMLParser.parseInputs(Unknown Source)

at beast.util.XMLParser.createObject(Unknown Source)

at beast.util.XMLParser.parseRunElement(Unknown Source)

at beast.util.XMLParser.parse(Unknown Source)

at beast.util.XMLParser.parseFile(Unknown Source)

at beast.app.BeastMCMC.parseArgs(Unknown Source)

at beast.app.beastapp.BeastMain.main(Unknown Source)

at beast.app.beastapp.BeastLauncher.main(Unknown Source)