# `type.assign_unknown`

Assignment target is not declared.

Area 3, [Logic](../topics/logic.md); not declinable; the next step is usually the agent's.

```jadpo
type Count = Int {}

function total(count: Count) -> Count {
    running = count
    return count
}
```

```text
error: `running` isn't declared
 --> main.jadpo:4:5
  |
4 |     running = count
  |     ^^^^^^^ not declared
  reason: An assignment changes a `var mut` declared earlier in this block or one around it.
  next: Declare it first, as in `var mut running: Count = ...` (agent)
  rule: type.assign_unknown
  help: https://jadpo.dev/docs/errors/type.assign_unknown

check failed: 1 error, 1 file
```