Controllogix LBL instruction question

We're working on a firmware upgrade on a couple of 1756-L55 processors.
The processors are currently running v12.x firmware but since we've upgraded our laptops to Win7 64-bit the oldest Controllogix firmware supported is v13.x.
Anyway, long story short...

We're getting an Error on a couple of rungs when we verify the program after firmware conversion to v16.x:
Verifying routine XXXXXXXXX of Program Sequential_Scan_Programs
Error: Rung 2, LBL: LBL instruction not first instruction on rung.
Error: Rung 16, LBL: LBL instruction not first instruction on rung.


My understanding is that the LBL instruction is always supposed to be used at the beginning of a rung.

Is this a non-critical error and the program should still execute? A case of poor programming practice and/or is it possible to use a LBL in mid-rung with no problems?


My next step is to do a verify on the original program to see if it's in there as well but I'm waiting a couple days yet to get one of our old laptops back in the office so I've got RSLogix5000 with v12 support.
The v12 firmware original program is working fine in the machine now.

LBL must, not should, be the first instruction on the rung....

I just created a V12 L55 file and tried to put an LBL as the second instruction on a rung, and rung verification produced the same error.

I cannot see a way in which the running file can have been downloaded with LBL not at the start of the rung, and can only deduce that the offline file has somehow been modified.

A follow up on this project...

Got one of our XP laptops back in house and I looked at the original v12.23 firmware program. No errors or warnings when you verify it.

BUT, in this project the couple routines that we're getting the post-conversion errors are protected source routines. I didn't know you could mix open and protected routines in a project. First experience with that for me. I'm betting that the source protection is what is hanging up our project conversion.
Our next step will be getting in touch with the OEM to see if they can help us out so we can get the firmware updated.
BTW these controllers are in Bosch SVE3800 baggers.


Thanks for the info daba! I was pretty sure that the LBL must be at the beginning of a rung but that error message was throwing me off of the trail.