Dell Venue 8 Pro 3G Sleep Issues

Hello! I just bought my Dell Venue 8 pro 3G tablet and everything works fine except the sleep mode. I cannot change my tablet to sleep mode because there is only the shutdown and restart option in the drop-down menu. I did some tests using powercfg command line tool and I just discovered that my mobile driver(hardware) prevents the tablet to going to sleep mode. Why is this happening and what is the solution to this problem?
