Why is the 'Contract Complete' checkbox greyed out?

Explanation:

The most likely explanation is that contract delivery tolerances are being enforced. Contract delivery tolerances prevent marking a contract as complete until deliveries against it exceed the tolerance level.

You can set the tolerances, or turn off this feature, in the Program Options. From the Utility menu, select Program Options. From the tree list, select Contracts, then Common. Use delivery tolerances is the first option on the page.