Recharging A/C system with vacuum pump

I'm pretty mechanically inclined and watch a lot of videos and read articles on recharging an A/C system using a vacuum pump and manifold. I hooked the low and high side on the system and pulled a vacuum for approximately 1 hour. I then closed the system up and waited 30 minutes to check for leaks. The system was sealed so I proceeded to hook up the can of r134a and purged the line to the can and then opened the low valve leaving the high side closed. The gauge read about 25-30 psi and I then started the vehicle and turned on max blower and A/C. The compressor clutch never engaged so I used a paper clip to jump the relay that controlled the clutch. This made the compressor engage but the it wouldn't suck in the r134a and it was as if it was still off. I don't know if its a user error or if there is something wrong with my system. After trying all afternoon I gave up and tried looking for reasons why and I found this page offering free advice. I hope you can help me out, I would appreciate it a lot. Thank you.