Hi

I talked to the guard about seeing the "big boss" and then went back to station. But when i talk to Guza. i can't get McCoy or Guza to mention the matter.

Bit of a spoiler so read responsibly :)

It seems that McCoy will ask the guard about how one goes about seeing the big boss if he either (or both):
- asked the Tyrell Guard about the victim
- examined the PC monitor in the booth outside the Grav Test lab.

He will only ask Guzza about arranging a Tyrell meeting if he examined the PC outside the Grav Test lab. The conversation with the guard itself is actually not a prerequisite.

Let me know if this helps, otherwise you could upload and share a save game on a cloud file storage service so we could investigate further.