while porting from qt3 to qt4 where should i define custom signals and slots

from qt3 to qt4 i have done porting through uic3 , qt3to4 tools. every thing is working fine but signal and slots are not working why?

i have to change any code ?
please help..

There is no change in syntax for signals or slots between Qt3 and Qt4.

There is a behavioral change in signal/slot connection across threads, but within the same thread the behavior is also the same in both version.

Cheers,
_