Quote from waltbx:
I don't think you need to worry about your pairs being lost, it's just the data associated with those pairs.
Here's what I'd do. I'd shut down PTF and try again. Copy and paste the script exactly. If that doesn't work, email Jason at PTF.
I too have some pairs that have very low or negative correlation, yet have good ratios. I don't understand that. Not well correlated, but very profitable.
Walt B
Because correlation is not the appropriate measure; look up co-integration. Ignore corr and focus on back-test results. [Although most will likely ignore me instead!]