adding additional parameters in bicep module

Need help with bicep module when when i set up container apps, how to control the value of the revision mode parameter, where the default value here is multiple, but then i need it to be set to single. getting error with this code-

properties: {
    managedEnvironmentId: containerAppEnvId
    configuration: {
      activeRevisionsMode: revisionmode == 'Multiple' ? 'Multiple' : 'Single'
      secrets: (!empty(secret)) ? secret : null
      ingress: {
        external: externalapp
        targetPort: targetPort
        allowInsecure: false
        traffic: [
          {
            latestRevision: true
            weight: 100 // set weight to 100 for all cases
          }
        ]
        ipSecurityRestrictions: ipSecurityRestrictions
      }