Arrow t337a cant connect to be able to unlock

i ve been trying since yesterday but no luck..cant connect with pc
To connect SM-T337A phone you have to perform the following steps:

1. Disconnect USB cable from phone.
2. Go to Menu->Settings->More->About Device.
   3.Tap on "Build number" 7 times to enable developer options.
3. Go to Menu->Settings->More->Developer options.
4. Turn on "USB Debugging" option.
5. Go to Calculator application. Enter "(+30012012732+" number, to get phone dial window.
6. Enter "*#0808#" number.
7. Select "DM+Modem+ADB".
8. Press Home button.
9. Go to dial window.
10. Enter "*#9090#" number.
11. Set "Diag config" to "[1]DM/DUM over HS-USB" value.
12. Restart phone.
13. Press "Read Info" in software.

Platform: Samsung Android
Selected port: COM1
Selected model: SM-T337A
Phone was not found on the selected port!
Searching for USB diagnostic port...
Connecting to phone on COM101
Port is busy
No diagnostic ports found!
Connecting to phone on COM21
Phone connection failed

i dialled *#0808# and #9090 but nothing popped up...usb debugging all set but no luck