dan231,
If the extension is up and working at the remote site then your problem is not with how it was created, but whether or not the extension conflicts with another extension in the other nodes.
What you can do to prove this point is try creating that extension as a new extension on your node. If it let's you do it then there is an issue, if it doesn't then you need to find where that extension conflict occurs within your node.
This is typically a simple process, IF the systems are maintained properly. It sounds as though you haven't been performing Imports/Exports every time you create a new extension, but it should take care of that for you over time. What you won't notice is whether you have issues with conflicts until it is too late.
Thanks,
TE