# Missing import for third party library

**URL:** <https://forums.unrealengine.com/t/missing-import-for-third-party-library/440956>\
**Category:** Plugins\
**Tags:** third-party-librarie, unreal-engine, Plugins, question\
**Created:** [January 9, 2019, 4:07pm UTC](https://forums.unrealengine.com/t/missing-import-for-third-party-library/440956 "2019-01-09T16:07:57Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![anonymous\_user\_354634ee](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_354634ee](https://forums.unrealengine.com/u/anonymous_user_354634ee)\
**Post date:** [January 9, 2019, 4:07pm UTC](https://forums.unrealengine.com/t/missing-import-for-third-party-library/440956/1 "2019-01-09T16:07:57Z")

</div>

I’m having trouble running my plugin

![264731-unknown.png](https://d3kjluh73b9h9o.cloudfront.net/original/4X/1/b/6/1b6eb4b73954a641a0c9002850fe61aaeb52a4d6.png)

And it’s probably because of this

```
[2019.01.09-14.46.38:567][0]LogWindows: Missing import: avutil-56.dll
[2019.01.09-14.46.38:567][0]LogWindows: Missing import: avcodec-58.dll
[2019.01.09-14.46.38:567][0]LogWindows: Missing import: avformat-58.dll

```

I’m loading in third party dll’s and UE4 can’t find them in the directories it searches through. From what I understand I should be able to bypass this problem by telling UE4 not to load the dll’s on start up and then fetch them manually with GetDllHandle. So I added these lines to my Build.cs to tell UE4 not to load the dll’s on start up

```
string[] dlls = { "avutil-56.dll", "postproc-55.dll", "swresample-3.dll", "swscale-5.dll", "avcodec-58.dll", "avformat-58.dll", "avfilter-7.dll", "avdevice-58.dll" };

foreach (string dll in dlls)
{
   PublicDelayLoadDLLs.Add(dll);
}  

```

Yet I still get the same “Missing import” issue, any idea why? Have I misunderstood what PublicDelayLoadDLLs does?