MAB you are great! what i've done earlier was wrong ( by the way i still don't understand why) . now i made the schematic exactly as you did, and even though it still gives me that gmin error, now the waveforms are correct, and they are displayed. Thank you very much!
i'll start reading the manual, i'm not as prepared as i thought

 

Check out Chapter 16 titled "Spice: Beyond the Basics".
It provides tips on Troubleshooting spice problems (including Gmin stepping errors).

 

Not to be a stick in the mud, but I fail to see the benefit of having:
R4, R2, C3, and R5 in this circuit.

As far as I can tell, the only benefit is more costs.

 

Not to be a stick in the mud, but I fail to see the benefit of having:
R4, R2, C3, and R5 in this circuit.

As far as I can tell, the only benefit is more costs.

Your right, They are not needed, forgot to mention that.
However, when I reread the posts, I missed this line:

"@ R!f@@ in my project i use TS555CN and because i didn't find it in circuit maker i tried to simulate with a normal 555 timer"

When I pulled up the datasheet, and did the number crunching, The simulated waveforms were way off
So I redid the drawing so that the waveforms closely matches the datasheet.

mitza: Note that I went back to the original (macromodel) 555, and the use of pin 7 (Discharge) per datasheet.
You never posted what you needed for the pulse parameters, so this is far as I can go

P.s. datasheet download here
http://www.datasheetcatalog.com/datasheets_pdf/T/S/5/5/TS555CN.shtml

 

You are simulating a Cmos 555, not an ordinary 555.

 

i realized too that they are not needed, this morning, just before presenting my simulation to the professor . he said it was ok. i will look further into it, anyhow, for now thank you MAB and everyone else!

 

You are simulating a Cmos 555, not an ordinary 555.

OP posted that the chip he had was a TS555C.
Datasheet states that its a cmos timer.
Therfore, picked cmos model to simulate