Unable to do usb bootstrap with 3945

Downloaded below file from bootstrap section of the APIC-EM IWAN app -

 interface GigabitEthernet0/2

ip address dhcp

no shut

!

pnp profile IWAN-PNP-PROFILE

transport http ipv4 xx.xx.xx.xx port 80

 exit

copy running bootflash:IWAN_RECOVERY.cfg

 The router is running on version 15.5(3)M2 .For some reason, its the router does not start with this configuration. Its just booting normally. Used 4451 as well with 3.16 code version and it worked perfectly. Also, in IWAN documentation, it says the supported version on ISR G2 is 15.5(3)M2a. But there is no such version (may be I am missing something)

 Check the name of the configuration file on the USB stick.  It should be ciscortr.cfg.