  The role of the entrance channel in the fusion-fission reactions leading to
nearly the same superheavy compound nucleus is studied in the framework of
dynamic model. The calculations are done for $^{48}$Ca + $^{244}$Pu and
$^{74,76}$Ge + $^{208}$Pb reactions which could lead to formation of superheavy
element Z=114. It is shown that for these reactions there is an energy window
for the values of the bombarding energy at which a capture probability is
sufficiently large. Together with the restriction coming from the intrinsic
barrier for fusion, it helps to find an optimal value of the bombarding energy
for a given projectile-target combination.
