How do you select multiple Ora trc files for import of trace activity ? (4287307)

I am using Benchmark Factory for Databases 5.7.1 and am trying to import 20 captured Oracle session traces ( trc files ) with 19 being 4 Mb in size and 1 being about 10Mb in size.

The intent being to replay the 20 captured and imported sessions. Things are going fine in terms of using the Load Scenario Wizard to import the trace files except when I reach the "Oracle Trace Activity" page .

The "Import entire trace file(s)" button is selected ( I wish to import all transactions in all 20 files during the 20 minutes period of capture ) and I want to import all 20 trc files at the one time.

However, for some reason I can't seem to select multiple trace files at this step and the next step only imports the one file which happens to be highlighted.

It doesn't make sense that I would have to go through the Load Scenario Wizard 20 times to import each of these 20 Oracle trace files individually.  

What am I doing wrong here?