Fastboot problems- Unlocking the bootloader drivers istalled

[Aris1]

Hi Guys,
I am new here sorry if I am posting this in the wrong section.
2days ago I flashed my xperia p successfully , I installed the s1boot driver all went well, but now I am trying to unlock bootloader to yes,I have downloaded SDK and installed google drivers, when I put on debugging mode on turn off the phone press volume down key plug in 1sec red light and green comes up for a minute then goes to changing mode,same thing happens if I not hold the volume down key just plug in ,
devise manager doesn't detect anything when its switched off detects the device only when on. Also when phone is off I plug in the cable holding volume down it doesn't search for any drivers, I tried factory restore erased all the data nothing changed. Please help!

[Thommo]

To unlock the bootloader you need to as said enter Fastboot mode which is whilst phone switched off Hold volume up and then connect the usb cable - By holding volume down you enter Flashmode which is different from Fastboot which you need to enter

[Fenomenon]

I have exactly same problem.
my phone is rooted (idk if this needed or not) and stock jelly bean installed.

I installed minmal adb and fastboot, I shot down the phone and connet to pc (debugging mode on) while pressing vol up key.
but nothing happens, it just went to charging mode.

I also tried kingoapp's "sony bootloader unloack" application. yesterday it saw the phone, it said dont plug the phone out, i waited like half hour but nothing happened. today it just say "failed"

sorry for bad english
thx for reply