Unable to Route Requisition approval based on DFF value

Summary:

We have a requirement where we would need to auto approve a requisition based on a DFF value but we are unable to achieve the requirement

Content (please ensure you mask any confidential information):

We have a requirement where in the requisition header, if the DFF value Mass Distribution Order is Yes then the requisition should be autoapproved

We have used attribute 13 for defining this DFF. Value can two values namely "Yes" or "No"

We have defined an approval rule where if header text attribute 13 equals yes then requisition should be auto-approved. But this is not working

The requisition is remaining in pending approval status. Please let us know how we can achieve this requirement