problem with the voltmeter in my digital cluster

hi friends. I wirting of my country PERU in southamerica. I make the transfer from my analog cluster to one
digital cluster in my dodge daytona 1989 2.5 turbo. I have done the conversion wiring and everything works OK in the digital cluster. there is only one problem, the voltmeter does not work, the symbol of voltimero (little battery) remains intermittent and only marks a line or two. the gauges of oil press and water temp, these two work perfectly. you can be wrong? ground? the screen is bad? the connection of ground or connected 12v wrong? I wonder if someone can help me with this problem. leave a photo reference. Hope someone can help me. Greetings to all of Peru. http://imagizer.imageshack.us/a/img922/8424/UPA62M.jpg