Lol! It happens!
For successful sublimation, the shirt needs to be white (or very lightly coloured) and either 100% polyester or at least a high mix of ployester if it's a poly/cotton garment.
You can sublimate onto cotton, or darker materials, but you need a different process to provide a white background to your designs, usually involving special transfer papers or an OKI laser printer with white toner (expensive!).