I cycle through all gears and none will engage

I replaced the transmission filter and fluid. I cycle through all gears and none will engage. The fluid is showing exactly between the hot and cold marks. I used the correct filter and fluid. I have dropped the pan two additional times to ensure the filter is set correctly. I allowed the engine to run for about thirty minutes. I did notice that the transmission temperature dash indicator was still showing cold, so I think it is not circulating through the filter and pump. I also disconnected the battery to clear the computer. Any advice would be greatly appreciated!