Entrances! :-(

I do not know why but my entrances never work. Normal entrances like caves or houses work normally but custom made entrances didn't work. I hope any one can explain to me how they working.

I assume you mean the custom gfx entrance (like Parallel Tower). Basically you need to make an exact corelation of 32x32 and even 16x16 tiles, to be able to position the yellow dot correctly, so that it is on the exact 32x32 place left up, and to be able to enter at all.
 
Further it is importaint what the type of tile is the one which can react as entrance (black empty tile). In most cases this is gfx block 254, type 0.
 
But it is also importaint what above the entrance is. Try to place the pyramid entrance so (in Alttp), that one brick is above it (entrance will not work). It will only work if the two bricks come together above the entrance. This is because such combination has a type 2 in-front settings for both gfx tiles just above the entrance, while one single brick has the plain type 1 or type 66.
 
Example with gargoyle grate in GoT. I've chosen gfx block 254 type 0 for the hole, but it had block type 1 above (one gfx unit above the hole). I had to change it to block type 2 and in-front effect. I also decided to make it so, that the left and right part of the entrance were in 2 separate mirrored 32x32 blocks, since I knew it could be the issue if having it in one 32x32 block.
 
Making a giant entrance, like in Parallel Tower, is of course even more complex and requires two (or more) yellow dots, and the same strategy as above, just expanded horizontally.

Here the picture
 

 
Relevant:
-gfx block A must be type2 in-front
-gfx block B must be type 0 (gfx block number 254, don't know if the gfx number is relevant)
-the yellow dot must be left up exactly as on the picture.
 
Both B and both A gfx tiles are not in the same 32x32 block, but in two mirrored ones (don't know if this is relevant).
 
I've put C to the same settings as A, just in case, but I don't think it's relevant.
 
I don't think D is relevant, but in this case it has the same settings as B.
 
The E can be plain type1 or 2.
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I've tested some more: houses and cave use the same global placement strategy, but they have type 1 at A. So type 1 is acceptable in this case. But that really doesn't matter. I make all entrances as above, and they work. If I don't make it as above, they usually don't work (once I had a type1 on A on gargoyle and it didn't work, some other time I had both A or both B or all 4 in one 32x32 and it didn't work etc).

I made ​​it exactly as you said and I just played around half an hour but it does not work :-( Can I Send you my rom and you try it? :-)

Yeah, sure. You know my mail? puzzledude@hotmail.com
I would actually had to see it, to be able to test it. But I know I had the same problem, and I could fix it in Alttp (custom pyramid area) and GoT.

I Found the problem. This is actually bad news as well. Tile types are irrelevant, which is odd (I concluded that with testing). All the entrances will work only if a series of 4 tiles is used under the yellow dot, starting in the lower-left part of the dot.
 
For instance the sequence for the cave is 491, 495, 495, 491.
The sequence for the big entrance in my picture is 305, 350, 350, 305. In your case it is not one of these sequences, so the entrance does't work. There are a lot of entrance sequences (every entrance in Alttp has one).
 
This is bad news, since you need to redo the gfx in order to fix this and choose 2 Spaces (block numbers in HM, tested to already form an entrance) on non-neutral gfx, which will always be reserved for all entrances, while reloading the gfx on them. This of course also means that every custom gfx, should be adopted accordingly.
 
For instance we choose 305 and 350 (those are spaces in HM). If entrance is not mirrored, 4 of those spaces are needed. So now when the gfx number is loaded into those 2 spaces, they must always contain half the entrance (usually at the very top - solid, of one gfx just bellow the top).
 
I hope however, there's some other way to make the entrance work, I just coudn't see any other way. I've send you the edited roms back (one entrance was fixed to work, same can be done with others), but some new global gfx strategy is needed, like described above to be able to enter in a custom entrance.
 
Irronically this is all fixed in Alttp, using its gfx or adopted gfx on the same place autofixes this. That's why it is not fixed on custom gfx.

Using the picture again with this new knowledge.
 

 
 
The sequence C A A C is importaint, the rest is irrelevant and can all be on type 0 if you want. In-front is also not importaint.
 
The tile type of C A A C is also not importaint.
 
What is importaint? The gfx block numbers (spaces in HM). C is block number 305, A is 350. C A A C is 305, 350, 350, 305. A sequence which forms an entrance by default (as it is in Alttp).
 
305 is on a 5th gfx spot, 350 in 6th, so non-neutral gfx (which coresponds to gfx numbers). For instance gfx# 59 in overworld will load pyramid tiles into 5th and 6th gfx spot. So the pyramid gfx needs to be adopted to form a 4 line sequence, which will be the entrance. All other areas should have it like so as well (if you should choose 305 and 350 for entrances).
 
For instance: 491 and 495 is for all caves, haven't yet looked at the house (and other) sequences.

I guess I came to the same conclusion as NEONSwift, without looking at his explanation. But after testing I realized it is just that one line which is vital. The sequence 491,495,495,491 is for caves. But there are various other sequences for entrances, who also work. For instance for Turtle rock it is 305,350,350,305. Haven't looked at others. But yeah, didn't know it is that complicated. I thought the yellow dot would do.