2-look OLL not working?!

[hellish73]

I have started learning 2-look OLL and I do the first alg to make the yellow cross and the yellow face doesn't match any of the patterns. One yellow block is always twisted the wrong way, for example:

When it should be like this:

It is like this:

What am I doing wrong?

 

[cityzach]

You twisted a corner, just twist the corner back so it matches one of the patterns.

 

[cubecraze1]

You have a corner twist
It means that one of you corners have been twisted in a solve and you have an impossible combination.

Edit: ninja'd

 

[FinnGamer]

You accidentally twisted a corner, making the cube unsolvable, take it apart and twist the corner to match the picture
edit: double ninja'd

 

[F perm]

One of your corners has been taken out and twisted. This happens accidently sometimes if you take it apart and put it together wrong.
Simply take it out, without breaking the cube, then place it back in twisted correctly.
The best way to take a cube apart is to turn the Up layer 45 dgrees, then pop out a U layer egde. You can then remove more peices. To replace, do that in reverse.
Also, if you have never taken apart your cube, you may have accidently done this by turning sloppily, which happens a lot on looser cubes.
EDIT: Triple ninja'd, but read my post any way, it good