'Step' and 'Step Over' doesn't work while debugging

Hi, i am new with Keil and STM32F407VG. I tried to run a simple code (blinking 4 leds). And it worked with no problem. Afterwards, i tried to learn some simple debugging basics. And I can't reach...
DS5 DEBUGGER ERROR(CMD441-TAD1-NAL85)

What does the following error message mean?! ERROR(CMD441-TAD1-NAL85): OS has locked out debug during OS save restore.
DS-5 debugger hover functionality not working

I'm using the DS-5 debugger in eclipse in Ubuntu with FVP models and when stopped at a breakpoint, when I hover a variable it shows me its declaration and not its current value. Does somebody know how...
debug indicator doesn't work properly and some variables show unavailable

When I debug my application with DS-5, the debug indicator doesn't point to correct instructions sometimes or jumps back. Some variables show unavailable, or show value later after one or two instructions...
Keil debugger mode doesn't work

Hello i'm new in this forum, I have a issue with keil, I try to learn more for adc and other things with the stm32f103c8 (I bought 4 it's very cheap XD), in the firts time I do the blink led, then I try...