I want to make animation in Expression Blend for Windows Store Apps as .gif images are not supported. So I have approx 30 png images. I made a storyboard animation in Blend by c
To have animation, you need to show many frames one after another with relatively high speed. The human eye sees something like 23 frames every second, so you need more than that to have smooth animation. Your idea of changing frames every 2 sec results in a framerate of 0.5, which is no longer an animation. Reduce the time between your frames to something like 0.05 seconds. Also, try to avoid sprite animation (frame animation, gif-style animation) altogether if possible.