Wash with deionized water to remove the destain so0lution and prevent fogging. Then extensively wash the gel for at least one hour with a number of water changes. Restaining can be carried out beginning with the addition of fresh silver reagent. Bands may be faint or absent. Increase wash steps.
Temperature is too low.
The developer precipitate sticking to the gel surface can cause mirroring. Be sure to decant first development solution as soon as the precipitate appears. Reducing proteins with dithiothreitol according to Morrissey may help. Dark uniform background, usually yellow. Oxidizer is not completely removed.