Looks like there are 12 Primary heater components in the branch. IDD branch object has input fields for 11 components and for more components extra input fields need to be added in IDD. Did you edit the IDD Branch object input fields as below?

below?
    A57, \field Component 11 Branch Control Type
       \note field is no longer used 
   A58, \field Component 12 Object Type
   A59, \field Component 12 Name
   A60, \field Component 12 Inlet Node Name
        \type node
   A61, \field Component 12 Outlet Node Name
        \type node
   A62; \field Component 12 Branch Control Type
       \note field is no longer used