sanukyadav:
1- I didn't use voltage divider ckt. (Will it results in this kind of error ?).
No. If you check Google Images, you will see the divider is used in only about half of them. It IS good practice.
2- I have used my own app which is created by using app inventor MIT,
A really bad idea, but apparently you got lucky. Special kudos to Cattledog is in order.
3- Red LED is blinking in some frequency when I scanned using a smartphone, I got the device ID listed in available BT, and I'm able to pair using 1234 pwd.
OK. This means Android <> Bluetooth is kosher. It does not mean Buetooth<>Arduino is kosher.
Check your Arduino/wiring Rx>Tx and Tx>Rx.
You might find the following background notes useful.
http://homepages.ihug.com.au/~npyner/Arduino/GUIDE_2BT.pdf
http://homepages.ihug.com.au/~npyner/Arduino/BT_2_WAY.ino