unresolved external symbol _IID_IHTMLFrameBase2

I have written code to get chosen tags out of an html document in a
running instance of IE. Everything works fine.

I am now trying to make it work with frames. I wrote the code and it
compiles, presumably it will also work as intended. The problem comes
with the linker. For some reason I get:

error LNK2001: unresolved external symbol _IID_IHTMLFrameBase2

I have included all headers that I can think of, but no luck. I figure
the error is quite simple to solve but I know very little about this
subject and am stuck.

Anyone could please point me in the right direction?

Thank you all.

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