The application you are installing requires 64-bit assemblies. You can find more information about the side-by-side assemblies in the Sequencer log file which is located in the following directory:
<App-V Sequencer installation drive> \Program Files \ Microsoft Application Virtualization Sequencer \ Logs
Install public versions of the required 64-bit assemblies on the computer running the App-V Sequencer before sequencing this application. You must also install the assemblies on the computer running the App-V client before you deploy this package.