Unable to fetch Sales Order details from App composer trigger on Install Based Asset

Summary:

Unable to fetch Sales Order details from App composer trigger on Install Based Asset

Content (please ensure you mask any confidential information):

We are unable to fetch Sales Order details from App composer trigger on Install Based Asset using an standard SalesOrderHeaderVO. Could you suggest on this issue?
The following steps are performed:

1. Navigate to App Composer > ERP and CRM Cloud > Install Base Asset object > Triggers
2. Create a ViewCriteria with below details
   def so= "547"
   def vo = newView('SalesOrderHeader')
   def vc = newViewCriteria(vo,' SalesOrderNumber = '+so)
   def iter = vo.findRowsMatchingCriteria(vc,-1)
   while (iter.hasNext()) {
   def r = iter.next()