Hyperterminal, Bluetooth,  Enhanced USART, PIC
You didn't give much information, but this smells like a serial port configuration problem.  Are you really sure the baud rate, number of data bits, parity, and number of stop bits is the same in both cases.  Probably not.  Since it's working with Hyperterm, see what it's set to, then make sure the Android is set to the same thing.

Also look at how flow control is handled.  If the unit is expecting to use RTS/CTS and the Android doesn't have those lines hooked up or doesn't have that turned on it could make it not work.