Change block attributes

Good evening,

I started in Autolisp, I try to tailor a program jefferyp Sanders (http://www.jefferypsanders.com/autolispexp_enti.html). The goal is to use AutoLISP to change the attributes of a block. This block contains various attributes (including "COMMUNE").

But it always return nil. I fit into the loop "(If (= (cdr (assoc 2 enlist2)) "COMMON") " but the attribute is not changed .. It must be simple but I have no idea ...

Thank you for your help

I leave my code:

(defun c:ModifAtt ()

(if (setq ent(entsel "\n Select a Block: ")) ;- Let the user select a block

(progn                                                     

(setq en(car ent))                                                       ;- Get the entity name of the block
 (setq enlist(entget en))                                              ;- Get the DXF group codes
 (setq blkType(cdr(assoc 0 enlist)))                       ;- Save the type of entity
 (if (= blkType "INSERT")                                              ;- If the entity type is an Insert entity
  (progn
   (if(= (cdr(assoc 66 enlist)) 1)            ;- See if the attribute flag equals one (if so, attributes follow)
   (progn
     (setq en2(entnext en))                                        ;- Get the next sub-entity
     (setq enlist2(entget en2))                                ;- Get the DXF group codes
     (while (/= (cdr(assoc 0 enlist2)) "SEQEND")        ;- Start the while loop and keep                                                                                                                   ;-  looping until SEQEND is found.

(if(= (cdr(assoc 2 enlist2)) "COMMUNE")
 (setq newVal (getstring "\n New Attribute value: "))
 (setq enlist2 (subst (cons 1 newVal) (assoc 1 enlist2) enlist2))
 (entmod enlist2)
)
        (setq en2(entnext en2))                             ;- Get the next sub-entity
        (setq enlist2(entget en2))                          ;- Get the DXF group codes
     )
    )
   )  ;- Close the if group code 66 = 1 statement
  )
 )   ;- Close the if block type = "ATTRIB" statement
)
)   ;- Close the if an Entity is selected statement
)