Problem is solved.
https://www.mql5.com/en/forum/293517#comment_9811172

MT4 DLL Not Support
- 2018.12.04
- www.mql5.com
MT4 also developed by its own company does not work why the DLL. Script under DLLSampleTester.mq4...

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The DLL made with c # does not work at mt4.
the following error occurs. I would appreciate if you help.
2018.11.27 17:15:12.066 Libdeneme1 EURUSD,M5: unresolved import function call
2018.11.27 17:15:12.066 Cannot find 'Add' in 'testme.dll'
(https://www.mql5.com/en/articles/249)
c# code and mql4 code included.