Help ac compressor not drawing in refrigerant upon charging

[Notnilc20]

Car: 1985 Toyota Corolla GTS (ae86)
R134
completely empty system
New Denso compressor
New condensor
New evap.
Pressure switch located on high pressure line

I half way charged the system first through the high side port with can upside down in a liquid state.....then i turned the engine over and started the ac and the clutch engaged and with a new can I attempted to charge the remaining quantity needed via the low port side as a gas......i purged and all was good.....then I opened the manifold and the valve handle at the low side port and nothing happened......the refrigerant was not flowing....yes I made sure i punctured the can with the tap valve and then opened it to let the refrigerant flow......but no luck......what is going on? My gauges read about 55 lowside and 100-200 psi on the highside and building pressure as i let the car idle.

Should I just charge the remaining via the high pressure port again??
Please help!

UPDATE: i went ahead and charged the remaining refrigerant via the high side as a liquid....so now I have the correct amt of oil and refrigerant in the system....however i am concerned because when I started the car and turned the ac on the low side still stayed the same at 55psi and the high side went from 150 to 200 then 250 ish and seemed to keep slowly climbing.....i then turned the car off. Is this typical? Does the low pressure stay the same like that and the high pressure side get that high normally? Do I have a stuck expansion valve? Thanks.

[bohica2xo]

Your low side connector is not depressing the schrader valve. You are reading the cracking pressure of the valve on the low side.

[Notnilc20]

Your low side connector is not depressing the schrader valve. You are reading the cracking pressure of the valve on the low side.

Cracking pressure? What do you mean?

So i might have been just reading the pressure of the can of refrigerant? So when I ran a vacuum....i might have just been sucking on the hose the whole time? I did run a vacuum with the high side open as well. So would that have been good enough to get the moisture out of the lines?

How can I be sure I get the schrader valve pressed? It is a retrofit r134 standard low pressure fitting....

UPDATE:
Well....i put the manifold back on the low side to see if i could get a reading and i got 45psi.....same reading on the high side. This was without the car running. That's good right? But when i put the high side fitting on and turned the handle to press the valve...it sounded like liquid was released and draining somewhere in the lines for a few seconds....is this normal?