Photographer Vs Lindsay Lohan

As TMZ first reported, a photog named Scott Nathan sued Lindsay's clothing line, 6126, claiming he was never paid for his work.

The lawsuit settled for an undisclosed amount back in December -- and according to docs filed last week, 6126 was supposed to making payments beginning in March ... but so far -- zilch. Now Nathan is asking a judge for an order to enforce the settlement -- attaching bank accounts, etc.