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# My rule with pattern-not doesn't work: using pattern-not-inside
One common issue when writing custom rules involves the unsuccessful exclusion of cases using `pattern-not`.
If you are trying to exclude a specific case where a pattern is unacceptable unless it is accompanied by another pattern, try `pattern-not-inside` instead of `pattern-not`.
## Background
In Semgrep, a pattern that's inside another pattern can mean one of two things:
* The pattern is wholly within an outer pattern
* The pattern is at the same level as another pattern, but includes less code
In other words, using `pattern-not` in your rule means that Semgrep expects the matches to be the same "size" (same amount of code), and does not match if that's not the case.
## Example
The [example rule](/writing-rules/rule-ideas/#systematize-project-specific-coding-patterns) `find-unverified-transactions` is a good example: `make_transaction($T)` is acceptable only if `verify_transaction($T)` is also present.
To successfully match the target code, the rule uses `pattern` and `pattern-not`:
But this rule is redundant. Both pattern clauses contain:
```yml theme={null}
public $RETURN $METHOD(...){
...
}
```
However, if you refactor the rule by pulling the container out and using `pattern-inside`, the rule doesn't work -- [try it out](https://semgrep.dev/playground/s/KZOd?editorMode=advanced) if you like!
```yml theme={null}
rules:
- id: find-unverified-transactions-inside
patterns:
- pattern-inside: |
$RETURN $METHOD(...) {
...
}
- pattern: |
...
make_transaction($T);
...
- pattern-not: |
...
verify_transaction($T);
...
make_transaction($T);
...
```
With an understanding of how `pattern-not` operates, you can see that this rule fails because the matches are not the same size. The `pattern-not` match is at the same level, but it is "larger" (contains more code).
If you switch to `pattern-not-inside`:
```yml theme={null}
- pattern-not-inside: |
...
verify_transaction($T);
...
make_transaction($T);
...
```
The rule successfully matches the example code.
## Further information
See this video for more information about the difference between `pattern-not` and `pattern-not-inside`.