Middlesbrough chief executive has blamed the "outrageous demands" of Benni McCarthy's agent Rob Moore for the breakdown of the player's proposed move to the club.
On Monday the Celta Vigo striker told Spanish sports daily Marca on Monday that only some finer points of the contract needed ironing out.
But Boro have pulled the plug on the move.
"If McCarthy's agent had not made such outrageous demands on behalf of the player he would probably be a Middlesbrough player now," Lamb told the club's website.
"Agents must realise that the climate in football is changing quickly.
"The gravy train is coming to an end and clubs are starting to be more realistic in their negotiations with players."
McCarthy scored for South Africa on Wednesday in the 3-2 defeat against Spain as the Bafana Bafana exited the World Cup.
Ten months ago Boro had hoped to sign McCarthy on loan but that swoop was abandoned when McCarthy was refused a work permit.
McCarthy, 24, joined Celta in 1999 from Ajax but has recently struggled to gain a first-team place.
However, he recaptured his best form during a six-month spell on loan with Portuguese club FC Porto.
Boro are set to unveil Italian Massimo Maccarone as Steve McClaren's first capture of the summer.
Although the 22-year-old Empoli striker's agent Paolo Fabbri claims that the deal has been clinched, Boro are yet to confirm it.
The £8m five year deal will equal the club-record figure they paid Aston Villa for defender Ugo Ehiogu in October 2000.