Forms :: Syntax For Nested Aggregate Functions?

I have a problem with a nested arrangement of Right, DLookup and DMax functions.

The function is for a default value in a text control

=Right(DLookUp("[SampleNumber]","tbldat14A_MasterSampleList","[SampleID]=" & DMax("[SampleID]","tbldat14A_MasterSampleList"))+1000001,6)

I am trying to retrieve the last record from a field SampleNumber which is alphanumeric (e.g. "AK005434") and then add a 1 to it as the next SampleNumber. I had previously used a default value in the txtSampleNumber control as

="AK" & Right(1000000+DMax("[Clip]","[tbldat14A_MasterSampleList]")+1,6)

where [Clip] was a field I have calculated in the table to chop off the preceding characters. Adding 1,000,000 and taking the 6 right hand values and concatenating with "AK" gave me the answer, though it is a but primitive.

This all worked until the SampleNumber value got out of order and blocks of SampleNumber values came in that were then followed by blocks of numbers with lower values (say AK005001-AK005050 followed by AK002001-AK002050).

Now I figure if I just recall the latest entry by DLookup and criteria of DMax on the SampleID (Autonumber Primary key) I could get at the value. I have done this to some success using default values in a series of unbound controls like

=DLookUp("[SampleNumber]","tbldat14A_MasterSampleList","[SampleID]=" & DMax("[SampleID]","tbldat14A_MasterSampleList"))

to get the SampleNumber I require, then a Right function to trim in another unbound box and then use that last unbound box as the default value for the txtSampleNumber control that is the entry for the data table. However, the unbound control box is only valid for the first record and does not update. So, I added a macro that closes the form and reopens it. This all works but is a bit agricultural. I would like to do a single nested function to the default value of the txtSampleNumber control box. Is it possible to nest Right, DLoopkup and DMax into one statement?