Why is dll reference removed automatically in c# project?

Question

C++ / C#

The situation is as follows:
There is a project created with Visual Studio 2010 c#.
In the Links section, I add a link to the service (to my dll). Before that, I wrote dll and added it successfully. Now I added a link to the dll, which I constantly change. As soon as I added it - I specify in the code using @[email protected]; . And everything seems to be fine, and the link appeared on the left in the browser, and when using @[email protected]; no highlighted errors. But as soon as I start compiling the project, there are errors in using @[email protected]; , that, they say, it was not possible to recognize the namespace, they say, indicate the link to the dll ..
I don’t understand what he needs from me, I tried to talk about this on the Internet, it didn’t help. We have to ask you, comrades!
Thanks in advance!

Answer 1

We unload the project (unload) and look in the code how it is connected, most likely some kind of condition has been added.