The pictures display dark on my Digital Pho...

The pictures display dark on my Optimus 7'' Digital Photo Frame despite the adjustments I have made using the settings buttons. The settings range from -3... 0 ... +3. Everything at +2 and below is too dark, but +3 displays the photos with far too much light. My photos do not display at the proper level of lighting despite recommended adjustments. Could my unit be defective? Please send advice to me (Deborah) at familyfoundationfirst@yahoo.com