Scott, I have no experience with Acutol. If you are sure that you followed directions correctly, you may need to do a little testing to come up with the correct ISO for your film/developer/equipment combination. For example, I expose Delta 400 (the old) at 320 and will probably need to test for the new formultion. Testing is a real pain but sometimes it is the only way to nail things down.(posted 8489 days ago)Of course, you could have just made a mistake somewhere in mixing. It is just hard to say. If your negatives are REALLY lacking in density this may be the case. At the very least you might try bracketing some exposure and then developing another roll.
BTW, I have always developed my own film but I have printed negatives that were shop developed for other people. To say that some of these were overdeveloped is vast understatement.