The type or namespace name does not exist

i have solution several projects in it, added 1 of these projects one, when using xxx.xxx; error:

the type or namespace name not exist in namespace (are missing assembly reference?)

i clean obj , bin folders, close open vs , rebuild them again, check under solution properties , see projects there , can add external reference using  the add reference option under references...

but still error!!!

any ideas?

thank you, found problem.

for reason classes namespaces in project importing renamed different project namespace...

weird... 

thanks.

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