Hey pes7md,

this is due to the vote value received is not in STEEM but in SBD/STEEMPOWER.

That means:

You paid 3.932 STEEM which is 12,5 USD

The vote you received is 2.51$ - meaning:

75% you receive as SBD and 25% as STEEMPOWER.

1,883 * 9,2 => 17,3 USD - 25% Curation (the curation on your post could even be lower) => 13 USD
0,625 * 3,2 => 2 USD - 25% Curation (could be lower again) => 1,5 USD

In total you received 14,5 USD and you paid only 12,5 USD.