bootcamp won't create partition - no error
Hi everyone! I have a MacBook Pro 13" early 2011. Recently I've changed my HDD for a SSD drive. I have the latest macOs High Sierra 10.13.3 and I'm trying to install Windows 8.1 via BootCamp Assistant, but when I set the Windows partition size (100GB) it says "Status: Partitioning disc..." and it stays like this forever. It doesn't return any errors messages and it doesn't freezes the computer. Any ideas of what can I do? Thanks in advance for your help! (sorry for the bad English)
MacBook Pro (13-inch Early 2011), macOS High Sierra (10.13.3)