The "Add 33x" macro pre-selects common menu choices for the 33x fields based on coding in the fixed-field and 300 $a. If it does not supply anything and only provides a drop-down menu of choices for these fields, you need to update your macrobook to the April 2013 version.
Download the April 2013 version here: https://help.oclc.org/Metadata_Services/Connexion/Connexion_client. The download link is "OCLC macrobook" in the first line of text. The file is named "oclc.mbk".
Right click on the link and select "Save link as..." Windows 7 users save the link to this path: C:\Program Files (x86)\OCLC\Connexion\Program\Macros
When asked if you want to replace the existing "oclc.mbk" file, select "Yes." Do not change the file name.