What that means is that payments or credits were not applied to invoices. From the AR transaction list go through the transactions and look for ones that reflect "unapplied". Then apply then. The easiest way is filter the AR list for the client. Then open the first transaction. Then just keep hitting next arrow to review each transaction. When all are applied you should be good. 

What that means is that payments or credits were not applied to invoices. From the AR transaction list go through the transactions and look for ones that reflect "unapplied". Then apply then. The easiest way is filter the AR list for the client. Then open the first transaction. Then just keep hitting next arrow to review each transaction. When all are applied you should be good. 

What if they all reflect applied? 

Then there is something else going on. Maybe some damage. Would need to run verification and look for errors or get eyes on to try to resolve 

I just ran a data verification and the message says: 

No Client A/R balance need to be rebuilt. 

No funds account balance need to be rebuilt. 

Does that mean that there is no damage? 

in Timeslips Administrator there is another database verification, that is the one you need to run. Didn't know which version of Timeslips you had so couldn't be more specific as they are in different places in different versions. 
If there are no errors then I would need "eyes on" to resolve the issue.