Well, the first thing to try would be to increase the memory given to EVO(select EVO and press Cmd-I, then go to memory and increase it to at least 20000k for large plugins). If your memory is high enough, then I'd check the EVO still works without plugs and if it's only your plug that doesn't work. Lastly, check that the type and creator of the plugin are correct. If you copied a sample plug, it should be fine, but if you just created a new resedit document and were editing that, you need to change the type and creator. So first try increasing memory, then check if EVO works without plugs, then check that Type and Creator are correct. If that doesn't work, then I don't know what will.
MickyBIs
PS-If the increasing the memory doesn't work and you need info on Type/Creator just post back here.
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Who is John Galt?
Ghoti spells fish!