However, the link was not ready on Monday and Patrick Robinson, the presiding judge, said the trial could not start.
No fresh date has been set for the trial to begin, but court officials told the judges a link was unlikely to be ready until April 28.
Robinson said: "This is not the first time we have been met with a disruption of the proceedings on account of the illness of the accused."
Stanisic and Simatovic's trial had been due to start last month, but was postponed several times because of Stanisic's ill health.
The court said in March that Stanisic was showing symptoms of osteoporosis, or thinning of the bones, pouchitis, an abdominal condition, and an intestinal problem ahead of hospitalisation for kidney stones.
A psychiatric evaluation also said Stanisic was "subject to a major depression with psychotic features" and showed "a clear wish to die".
The trial of the men is the first since the trial of Slobodan Milosevic, the late former Serbian president, which will consider the extent of Serbia's involvement in the 1991 to 1995 war in Croatia and the war in Bosnia (1992 to 1995).
The case against Milosevic ended without a judgment when he died suddenly in March 2006 just weeks before the trial was due to end.
Prosecutors hope this case will show there was a "joint criminal enterprise" of Serbian politicians, including Milosevic, aimed at "the forcible and permanent removal of the majority of non-Serbs, principally Croats, Bosnian Muslims and Bosnian Croats, from large areas of Croatia and Bosnia".
Stanisic climbed up through the ranks of Yugoslav intelligence, known as the DB, starting under Josip Broz Tito, the communist leader, serving as its head from 1991 to 1998.
For seven years he was one of the most important officials implementing the policies of Milosevic who was then president of Serbia.
|Simatovic was a member of Serbian |
intelligence for 23 years [AP]
Simatovic was a member of the DB intelligence services between 1978 and 2001 and directed the special forces division.
He is also known by his nom-de-guerre Frenki.
Because of the many links their case has with the Milosevic trial the judges have ruled that the parties can have access to part of the testimony from the trial of the former president, which had been confidential up to now.
In 2005 the indictment against Stanisic and Simatovic was amended to include charges related to the 1995 Srebrenica massacre of some 8,000 Bosnian Muslims after video footage allegedly showing Serb special forces involved in killings there surfaced in the Milosevic trial.
Stanisic, who was seen as a moderate among the Serb officials in the 1990s, is accused of organising the Croatian Serb troops who rebelled against Croatia's declaration of independence in 1991 and co-ordinating the Serb forces in Bosnia.
He was sidelined in 1998, a move which political observers attribute to Milosevic's wife, Mira Markovic.
Stanisic and Simatovic were transferred to the International Criminal Tribunal for the former Yugoslavia in March 2003.
They were allowed to await the start of their trial on provisional release in Serbia, but reported back to the UN detention unit in February.