Chlorine not in pool!

Hi I'm having a plethora of problems with chlorine. We opened our pool about a month ago and we continue to have an absence of chlorine even when we have put a total of over 15 bags of shock into our 40,000 gallon pool. The water is still cloudy (blue) and nothing seems to be working. We have used test strips and also brought it into a professional tester. here are the results:

Chlorine:0
TCI:3
ALK:80
PH:7.2
Total Hardness:100

Our pool is vinyl with a pump that is sand and 2.7 sq. ft. And our pump pressure is only 10, it usually is 18ish (is that a problem?) How can i resolve this problem?

Odds are that the chlorine levels are too high and are bleaching out your test strips. You don't say what method the pool store used to test, but if it's not drop-based, then that could be the issue there, too. Another possibility is that you have a huge chlorine demand from CYA that was converted over the winter to ammonia. When that happens (and it's happened to a lot of folks this year), it takes massive amounts of chlorine to overcome. What was your CYA last year, and what is it this year so far?

Have you tried using a cheap OTO kit from WalMart (uses red and yellow drops for pH and chlorine). Absolute worst case, you can dilute your pool water with distilled water and test that, and at least get some confirmation of whether or not there is chlorine in the water.

We did take it into a store where they used a machine and it said 0 also

You've got a big investment in your pool, now go a little more, get a Taylor K2006 kit and test the water for yourself. If you don't have this kit, then you're wasting money and the good folks on this site cannot help you because you're flying blind.

FYI the machines at the pool store can be seriously wrong. take a sample to 3 stores and see how far apart their results are. When they try to sell you something just tell them you already have some.