Usually this kinda error is displayed when the downloaded disk image file is corrupted. Before opening Image file for installation , Mac OS normally verifies by checksum to make sure the downloaded file is good to go. You can skip this process, but if the disk is really corrupted even little bit of difference , it might later affect the performance of Apps,
If it is okay for you , you may try downloading file again.
Clear Tmp folder and then redownload the file again and try to install.
If the Mac OS is El Capitan, for confirmation purpose set the Gate Keeper settings to Allow from Anywhere temporarily and then try to install.
" Caution" : Make sure to set it back to : Mac App store and Identified developers , once the installation is successful , It is very important.