A separate supply voltage (VCC1) is provided for the logic input circuits to minimize device power dissipation.
Supply voltage VCC2 is used for the output circuits
i found this on the first page of the data sheet 
http://www.me.ucsb.edu/~me170c/Sensors/H-bridge_sn754410.pdf
so wat are you upto ?
and check the wiring most of the problems are causes by not wiring correctly