One of the answers to Robert Crawford’s first Assembler quiz included this story from Bruce Roy at the University of Connecticut:
I can’t remember who complained but I remember that he was kind of sharp guy doing some research on our system. He actually said that there was a bug in the Load Address instruction. Peter Furmo, who received the complaint, took it seriously for about 10 seconds. Then, he reasoned that if there was a bug in that instruction, OS/MVT would not be running which, of course, was not the case.
Crawford’s moral of this story: The error is probably in your code.