Tottenham's pursuit of Cruzeiro's Bolivian star Marcelo Moreno could be undone by his complicated registration.
"The proposal was well short of what we expected," said Perrella, whose club only partly own the player, with a third party having a proportion of his playing rights. "Of course they should return to make a new offer but, until now, they haven't."
The complicated ownership issue may prove a stumbling block in any potential deal given the furore which erupted over the ownership of, among others, Carlos Tevez and Javier Mascherano when they joined West Ham last year.