Cant invite people from trade site

Higuys,

ihave problem with trade site, after direct whisper work but icant invite or noone can invite me from site,

i see them in my party only after pressing J, but cant porton them cant interact, and dont see icon ofthemon my left top side, like when i am in party with friends,

that means icant tradefrom site,

can youhelp me?, thx