Texture is a stereo effect. Therefore, it must be loaded as an insert plugin and not an instrument. Some DAWs will also not permit you to load Texture onto a mono track. If you do not see Texture in your list of insert plugins, try re-scanning your plug-in folder (or quit and reload your DAW).
If you are using PC, check which folder your DAW expects to find VST2 plug-ins in, and that this folder contains Texture.dll. If it doesn't, reinstall Texture, taking care that you set the VST plugins folders correctly. If you still experience problems, please contact support.