Problems with .tar file

Hello, I write from Spain and I'm novice in Linux World. I have a problem processing .tar file. When I write command "tar xvf .tar" to extract the file qt-1_42_tar.tar, then computer return then next error message: tar: Hmm, this doesn`t look like a tar file tar: Skipping

Problems with .tar file

Hello, I write from Spain and I'm novice in Linux World. I have a problem processing .tar file. When I write command "tar xvf .tar" to extract the file qt-1_42_tar.tar, then computer return then next error message: tar: Hmm, this doesn`t look like a tar file tar: Skipping