You had specified that you are using the single schema, so the rules and data schema configurations should point to single schema name as shown below,
<simple name="java:/prconfig/database/databases/PegaRULES/defaultSchema" value="pegarules"/> -> here you should give your schema name
<simple name="java:/prconfig/database/databases/PegaDATA/defaultSchema" value="pegadata"/> -> here you should give your schema name
Note: This information is provided based on the high level overview of your configuration file with reference to the latest Pega version as i am not aware of your version of pega. So, i would suggest you to cross check with the installation guide for the version which you are trying to install so that it will be more near to your configurations for cross verifications.
Hope this information might help you to resolve your issues.