Try to use serial interrupt for recieving the acknowledgement.
For that u have to initialize as ES=1 in ur UART function.
And provide 3Sec delay for recieving acknowledgement.
And then we are also facing problems on working with search command while google it we find that data sheet itself having some error in that they said that higher and lower byte for the search commands are interchanged and then by trail and error method the search command executed succesfully.
The arguments for the search command is
unsigned char search_template =
check sum 0X00 0X0f
while passing the arguments to the module higher byte and lower byte should be iterchanged and for check sum calculation the lower byte will be added to its respective lower byte.
i hope this might help you.