The former Oldham man, who worked under Dickov at Boundary Park, penned terms at Oakwell on Tuesday after previously beingoffered a deal at Rovers.
But Dickov withdrew his interest after the 24-year-old discussed terms with Rovers' South Yorkshire rivals.
Dickov said: "I made an offer to Jean before we travelled to Portugal but while we were away he said he was going to speak to Barnsley.
"I explained that if he did, I would not be proceeding with bringing him to the club, as I only want players who are 100 per cent committed to Doncaster Rovers."
- Doncaster Rovers