Why won't the A/C take a charge? Is it clogged?

I put in a jumper to engage the clutch. It engages and sounds good, but low side pressure reads low @20psi and it will not take a charge. Does this mean I have a clog? Any other info would be helpful.

There is a leak somewhere and the only way to find the leak is to put in a leak dye showing green spots.

My 2003 does the same thing. It registers 25 on my gauge. When I try to charge the system, nothing happens. The truck is running with max ac on and clutch cycling.