Error: template instance does not match template declaration

[Vitalii via Digitalmars-d-learn]

Hello! I am getting the following error:
```
inst.d(8): Error: template instance `Worker!(Mode.Inspect)` does 
not match template declaration `Worker(mode : Mode)
```
when compile next code:
```
enum Mode { Inspect, Execute }

class Worker(mode : Mode) {
        this() {}
}

void main() {
        auto W = Worker!(Mode.Inspect)();
}
```
Can anybody suggest to me what I do wrong?