Source Hard Drive Size Wrong

Prior to buying True Image 2016 I want to try it out. I own a Power Mac 2013 with 64GB of memory and a 1TB internal SSD drive. I just updated to Mac OS X 10.11 (El Capitan). In addition I have activated Bootcamp and installed Windows 10 professional. The partition sizes are about 300GB for Mac OS X is and 700GB for Windows. I have downloaded both versions of True Image 2016 (for Mac and Windows). When I want to backup my internal hard drive to an external drive, True Image (both versions) shows me the internal source drive with a size about 530GB. I did not want to proceed the backup, because both my partitions are precious to me. Ho come? What do I need to do in order for True Image recognizing my partitions right?