It's been nearly six years since the sister duo known as Nina Sky released their self-titled debut. Where's the follow-up? It's nowhere in sight.

In a series of tweets recently, according to a Rap-Up.com report, the sisters revealed ongoing problems with getting their label, Polo Grounds Music, in regard to the release and support their music.

This week, Nina Sky explained that their album has been ready for months, but say Polo Grounds refuses to put anything into motion.

"Starting a new campaign today... 'Nina Sky Doesn't Play Polo,' " they tweeted (@NinaSky) on Wednesday (March 10). "For months we've had a complete album, ready for release. Y'all wanna know what's really goin' on? Nothing [and] that's the problem.

"We released [two] videos and singles without support from our label. All good... Stayed positive. After months of no movement, we asked to be released [and] still nothing. No acknowledgment from the President of our label, Bryan Leach. Bottom line, we want to be released. If you're really down with our movement, holler [at] Bryan Leach."

According to Rap-Up, the duo signed with Polo Grounds Music in 2006, after an amicable release from Universal Records. Since then, Nina Sky says Leach hasn't held up his end of an agreement they forged when they signed on the dotted line.

"Upon signing, [Bryan said] he wasn't gonna do what Universal did and shelve our [second] album, [Starting Today]," Natalie told the website. "He was gonna get us in the studio, we were gonna complete our album, and we were gonna release it. Now obviously we don't expect that to happen overnight; it takes time and we have to get in with different producers. It took like two years to complete [the album] to the point where we were happy with it. He didn't stay true to his word."

Natalie continued, explaining that they've filmed and released two music videos on their own, without the support of Polo Grounds, but says the label failed to move on the buzz around the two songs. Now they ask: "Why be signed to a label if they're not gonna help you?"

The duo say they met with Leach over three months ago to discuss their situation, but since then, they've been getting the run around.

Stay tuned...