Problem in Swamps - Syslov and Cold ignore me

The first time I entered the Swamps I completed the task given to me by Lector and completed it successfully; but then I exited the Swamps having decided to complete other tasks that had accumulated. Much later (after Army Warehouse) I returned to the Swamps and headed to Dan in the North east where he was indicated on the map, but he was not there. I headed to Clear Sky base. Cold gave me no dialogue and just spoke Russian; Syslov just completely ignored me. Only Sviblov gave me some tasks. Can anyone suggest what is wrong. I have proceeded to far in completing other quests to go back.

Thanks for any help.

Dan won't appear until you have done a couple of tasks for Sviblov.

Spoiler:

 

"Find a Controller’s Brain" and "Find a PKM machine gun"

I don't know why Cold and Syslov won't talk to you, but it may be because you didn't visit the base immediately after helping Lector. Try again after doing Sviblov's tasks. Were you able to talk to Vasily the repair man?

Some of the recorded (spoken) dialogue is in Russian and some is in English. However, all tasks and other important information can be found in the written text, which is all in English.

Yes, Vasily talked to me. I will continue with the actions you suggest. Thank you for responding.

It appears to be working or proceeding as it is suppose to; When go to the Swamps I get the info message to see Dan (which is what I proceeded to do the last time and could not find him; then went to ClearSky base and experienced my problems) but this time I went to the base immediately and proceeded to talk to Syslov and I had dialogue from him. I assume the problem has been corrected by the change in sequence of this action. I will continue to follow the sequence of steps you indicated; thanks for the help.