Default (HELP)Sony ADB Interface

Guys, i need help.. I'm trying to unlock my bootloader. And when i'm going to fastboot my device, My computer says installing device etc.. Then it says was not succesfully installed. And when i checked into My Computer --> Settings --> Device manager. The Sony ADB Interface has a Yellow exclamation. (look at the picture) i think that's the reason why i can't fastboot or flash an FTF file before. I've tried to uninstall it So, if you could help me that would be great.. Thanks!