[JRTJH]

As sourdough said, you probably haven't dumped the galley gray tank. If you look under the trailer, just forward of the axles on the road side, you should find the gray tank dump handle. On the photos I can find of your trailer (Springdale 270LE) there is a decal on the trailer slide, just under the dinette window that matches the size of the two dump valve decals on the rear roadside corner of the trailer. My guess is that decal says, "Gray water valve" and is in line with the galley gray water tank valve.