IF THEN conditional failures in ver 3.83?

[Forex Trader]

We have written extensive code for Version 3.83 build 6231 but seem to be having problems with the system ignoring some of the conditions listed in our if then conditional statements. Seems to be hit and miss, performing function (modify, delete, setorder etc) without meeting all of the listed condtions. Syntax is correct.

Is this a common problem? Or just our fault?

Can code be too long or complex? Is there any comprehensive documention on ver 3 ( more in depth than in support link?)

Would appreciate any assistance