Wrong inline filter weight or order?

Hi, I'm having a weird behaviour with inline filter.

This is the situation:

1. In my site I use inline filter for images.
2. For general purpose -emoticons, style changes, etc...- I use Custom filter wich is based in Regular Expressions "language".

I'd like to render picture captions at the bottom of them. So, I need to catch the tags title="this is the title" and width="xxx" from html'd inline images. The process should be simple:

1. Convert [inline:file=title] to proper html code with inline filter.
2. Catch the required tags with custom filter and manipulate them.

So I set up the filter's weight to inline=1 and custom filter=10. Just for testing purposes and to ensure the regular expression used in custom filter is right I'm just trying to transform "alt" (without quotation marks) from < img src="..." alt="..." ... into "foo".

And here is the problem, nothing changes. As I said, I use custom filter for other tasks and it works right so I assume there is any kind of weight problem with inline filter.

Does anybody has information or suggestion about this issue?

Kind regards.