The adverbial suffix –like- is translated ‘to fail to X’.

Nesakam eletupuyosamlikesuna.

Nesakang eletsufuyosanglikesuna.

I failed to deliver the letter.

The adverbial suffix –likeku-, composed of –like- and –ku-, is translated ‘to do X successfully’

Nesakam eletupuyosamlikekusuna.

Nesakang eletsufuyosanglikehusuna.

I delivered the letter successfully.

The suffix –mulu- is translated ‘to do X in vain’. This suffix is not the same as –like-; -like- places emphasis on the failure to do X, while –mulu- places emphasis on the futility of the action, whether completed or not. The futility need not be the failure to do X, but possibly the futility of accomplishing X in the face of Y.

Epepipusummulunama.

Epepipusummulunama.

You will learn it in vain. (You accomplish the learning, but not the task for which you acquired the learning.)

When –mulu- is combined with other adverbials to created new adverbials, however, it does have the sense of failure. The suffix –muluyam- is translated ‘to try’ and is composed of –mulu- ‘in vain’ and –yam- ‘to be able’. This suffix requires the imperfective aspect.

Eki epuluwepumuluyamtumumo?

Echi efuluvefumuluyangtsumumo?

Have you tried to find it?

The suffix –muluka- is translated ‘to fail to do what one has resolved to do’. This suffix requires the perfective aspect.

Eki nimulo elekelomulukanana.

Eki nimulo elekelomulukanana.

I have failed to do many good things that I had resolved to do.