The National Institutes of Health has announced that it has chosen to not renew its $30 million deal with the NFL to conduct research on the link between brain disease and football. According to the NIH, the decision to not renew the contract—which will end on Aug. 31, 2017—comes after the NFL proved uncooperative to research and has failed to contribute all of the money it promised at the outset. Approximately $16 million of the original donation reportedly remains unused.

“The NFL's agreement with [the funding arm of the NIH] ends Aug. 31, 2017, and there are no current research plans for the funds remaining from the original $30 million NFL commitment," the NIH said in a statement, according to ESPN. "NIH is currently funding concussion research directly.”

The announcement comes just days after a study published in the medical journal JAMA and conducted by Boston University researchers showed chronic traumatic encephalopathy (CTE) in the brains of all but one of 111 deceased former NFL players.

In 2012, the NFL promised $30 million dollars to the NIH for brain research; according to ESPN, the donation was “the largest single donation in NFL history.” The NFL’s donation was widely praised as a sign that the league was finally willing to understand what the long-term effects of brain injuries are on its players.

Besides failing to contribute and properly allocate the large amount money it promised, reports have surfaced that the NFL attempted to influence research in its favor. According to ESPN, this is another reason why the NIH won’t renew its contract with the NFL, specifically citing a “bitter dispute in 2015 in which the NFL backed out of a major study that had been awarded to a researched who had been critical of the league.”

This “bitter dispute” was outlined in a New York Times report in May 2016 that explained the findings of a Congressional investigation into the NFL’s intentions. The committee found that the NFL had attempted to “steer the study toward a doctor with ties to the league.” The study claimed that the NFL “was privately attempting to influence research” all the while “publicly proclaiming its role as funder and accelerator of important research.” The NFL denied these claims.

It also appears that the NFL’s gift came with more restrictions than initially thought. The Washington Post reported this week that Democratic members of the House Committee on Energy and Commerce have written a letter to Roger Goodell, the NFL Commissioner, asking him where the last $18 million dollars have gone.

The NLF released a statement in response: “We are currently engaged in constructive discussions with the [NIH] regarding potential new research projects and the remaining funds of our $30 million commitment.” The statement also went on to claim that “in September 2016, the NFL pledged $100 million in support for independent medical research and engineering advancements in neuroscience-related topics. This is in addition to the $100 million that the NFL and its partners are already spending on medical and neuroscience research.”