This typically occurs where a journal has been uploaded from Access Office Integration and It is likely that there are data irregularities within the journal. Some things to look out for are:
Red text signifies an issue with the values entered.
Lines may have zero value and so cannot be posted.
The journal does not balance - this can be checked via the Debit Credit values in the header area.
There are extra decimals in the data that may show as Red text in the value fields, but cannot be seen. This can happen where data is copied from formulae with multiple decimal places - particularly if uploaded from AOI.
Investigation/Solution:
Check the journal line by line, reinputting the data if necessary.
Consider deleting the journal and starting again.
Check the source if it is from an import, to ensure that all is in order.
For further assistance please raise a new case online with details of the journal, and the database affected..