Agent Beppe Bozzo feels Inter Milan are running into problems with Wesley Sneijder due to confusion over his contract.
Sneijder faces being sold next month after refusing to take a pay-cut.
Bozzo, who is the agent of Antonio Cassano, said: "The assumption when you sign a contract is that it now provides for a number of years.
"But over the years many things can change, so at the beginning of an agreement it is necessary to establish the value of a player and fix everything.
"For example, with the bonuses so to avoid problems like Sneijder."