DataSet scope

Having a problem with the scope for DataSet.
This is what I'm doing.

Fetching a zip from a file of zipcodes.
Passing it to the url.

Extractor pattern 1 looks for the place in the code that contains 12 months of data, and saves that portion of the page to ~@YearData@~.
Fine.
Calls "DataExtract" script "after each pattern application"

The "DataExtract" script starts with -
DataSet mydata = scrapeableFile.extractData(dataRecord.get("YearData"), "get_1_month");
to extract each month from the captured portion (YearData) using the "get_1_month" pattern.

And it works great.
The log shows the 12 months of data as a big chunk in DataRecord 0, and then after the DataExtract script is run, there is a separate DataRecord (0,1,2,3...11) for each month with all the individual values assigned to the variable names in the pattern.
Very cool.
But then the script comes to a halt with an error message.

for( i = 0; i < mydata.getNumDataRecords(); i++ )
{
// Store the current data record in the variable myDataRecord.
xrDataRecord = climdata.getDataRecord( i );

// Write out the data to the file.
out.write( session.getVariable( "Zip" ) + "\t" );
out.write( xrDataRecord.get( "Monthabbr" ) + "\t" );
out.write( xrDataRecord.get( "High" ) + "\t" );
out.write( xrDataRecord.get( "Low" ) + "\t" );
etc.

The error message was: Attempt to invoke method: get() on undefined variable or class name: xrDataRecord : at Line: 15.

All the data is there, sitting in the DataSet.
I just can't access it, and I think it must be due to the scope of the variables.

Suggestions please!
Thanks.