Screws wont screw

[MaverickShev]

First of all hello and sorry for my poor english,
it sounds stupid but i have a weird problem
today i disassembled my T420 and when i wanted to put it all together these 2 M2.5 × 6mm screws from the image wont screw, they don't "catch" to anything, it's not the first time i disassemble it but it's the first time it does this, i searched a lot on the internet but couldn't found anything, i tried to search the room for some piece missing but nothing came out.
Please help me, thanks in advance.

[brchan]

Are the hinges seated properly? Look into the screw hole and try to see if there are any obstructions.

[RealBlackStuff]

Are they long enough, did you perhaps switch them with another pair?

[MaverickShev]

Are the hinges seated properly? Look into the screw hole and try to see if there are any obstructions.

I didn't touch the hinges, there are no obstructions, the screws go all in and they're the longest screws that came out of this laptop

EDIT:
This is a photo of the screw hole from the top(best angle i can do)
With the screw full in the hole it can't be seen from top
http://i.imgur.com/6emmYet.jpg

[RealBlackStuff]

There are 2 holes near one another.
The ones closest to the edge (#1 on that pic) are for the hinges.
The other ones need the keyboard bezel in place, before they find their "grip"

[MaverickShev]

There are 2 holes near one another.
The ones closest to the edge (#1 on that pic) are for the hinges.
The other ones need the keyboard bezel in place, before they find their "grip"

The holes for the bezel have shorter screws and i don't have problems with them

[brchan]

Are you sure you are using the correct screws? They shouldn't fall completely into the screw hole (too narrow of screw). All thinkpads I have worked on IIRC used thicker and slightly shorter screws for the hinge, which are for the screw holes you are having issues with. They probably shouldn't be the longest screws for the entire laptop.

EDIT: Judging by the HMM, the keyboard bezel/palmrest uses longer screws than the hinge. It looks like you may have switched them by mistake.

[MaverickShev]

Are you sure you are using the correct screws? They shouldn't fall completely into the screw hole (too narrow of screw). All thinkpads I have worked on IIRC used thicker and slightly shorter screws for the hinge, which are for the screw holes you are having issues with. They probably shouldn't be the longest screws for the entire laptop.

They are in fact one of the shortest screws
But they are the thickest didn't thought at this
Problem solved, thank you everyone for your help and sorry for wasting your time

little edit: is it normal to feel very dumb after this?

[RealBlackStuff]

Yup.
Next time draw a picture of the base and its screw holes, then tape the screw on the matching drawing-hole.

[jaspen-meyer]

"M2.5 × 6mm" means the screws use the METRIC system and they are 2.5mm in diameter and 6mm long.
Try a Vernier caliper. You can get a plastic one for the cost of a postage stamp.