When I compare my inventory gl acct #'s to my inventory value report, the numbers do not equal.  The net effect is equal, but the sub categories are not.  How do I correct?

We balance our GL accounts for inventory with the value reports every month.  We are seldom off by more than $30  total for our 5 accounts.
Do you print your Value report by GL account? This is the only way to get a total that will match the GL account you are looking at.
As far as the accounts not matching the value report if you are printing by GL account, you may have some non counted (type N) parts that use a counted part class code.  The transactions hit the GL in but the part will not show up on your value report because there is no on hand quantity maintained for N types. Another reason I have found that the accounts don't match is if for some reason you issue or make adjustments or receive a PO at $0 cost otherwise incorrect cost ( for instance if you go negative  the average cost can be  off for the issue process).  
I am sure there are other reasons why the accounts would not match, I just can't think of them.
Hope this helps.