So, this is very likely an extreme new player problem, I'm sure, but I can't find the solution anywhere. I'm in the process of doing the tutorial found on the creation kit wiki. I did a big chunk of it, saved it as testquest.esp, and came back to it later to continue. I went to Data, loaded testquest.esp, and continued my work. However, when I went to save again, under testquest, it said "File 'testquest.esp' is a master file or is in use. Please select another file to save to." So, I saved it under testquest01.esp. However, when I loaded that file before playing Skyrim, only the changes I had made since last time, the ones I made between saving under testquest and testquest01, appeared in the game. So for example I have the one room I added, not the entire dungeon I had been making. Loading testquest to Skyrim obviously just loaded the dungeon before the new changes, as I hadn't been able to save the changes to that file. Further, if I close out the editor and reload testquest01, only the rooms I've added and changes I've made appear. Am I doing something wrong while saving? Am I loading the files incorrectly. Any help would be greatly appreciated, as I can't see how to proceed without a solution. And again, I'm sure the answer is something super simple and obvious that I'm just not getting.

Are you playing the game while saving? You can't save the mod while it's loaded in skyrim. That might be part of it.

No, I didn't have Skyrim running while saving, but I -did- find the solution. I just had to make testquest the active file when I loaded it. Thanks though!

I am having a similar issue that i can create and edit a mod, it is saying that it saved but when i load up skyrim i cannot see the .esp file i created.

StonecoldMcNasty, it sounds like you are not setting you mod as the active file when you load it up the second time in the CK. In saving again with testquest01, having loaded the resources from testquest, you have essentially made a mod for your mod and will require both files.

When loading the mod in the CK make sure you select testquest and select set active file before loading.

Edit: Just noticed you already found the solution. Nevermind