Generally a leaking line will not pump up, much like a punctured balloon. A spray bottle of soapy water will be your friend discovering the issue.
If the bag does not raise at all, check to see that the pump continues to run. If it cycles, then adjust the control's position. Follow the air lines from the bags.
If the air pump runs constantly, then you have a major leak, a damaged air line, omitted O-ring, etc.
The most common problem with leaking air bags is not the bag itself. The most frequent issue is the O-ring on the air lines. I will assume that the new bags came with new O-rings? Did you replace the ones at the pump and at the Tee? O-ring problem are usually slow, sometimes over night.
Hope this helps.