Loop in process model

Need a loop for multiple texts. To test the loop just made a dummy loop like below

Start node:
Process variables : array(Text, multiple, {"a","b", "c"}), iteration (Number, Integer),  len(Number Integer)

Set len :
Set output: expression: = length(array), stored to: pv!len 

Properties: Delete after execution

XOR:
=pv!iteration>pv!len true End NOde
Else: Text Doc From Template

Text Doc From Template
save a document

named: pv!iteraion

description: pv!iteration & array

Properties: Delete after execution

Increase Iteration:
Set output: expression: = pv!iteration+1, stored to: pv!iteraion 
Properties: Delete after execution

But I can see the it stuck at XOR after 1st iteration. Why?
Let me know if you want more info.