AnnPhil,
If i understand your problem correctly i believe the following may help you. You essentially want a 'label' on a report to be conditionally formatted dependent upon a field being blank (IsNull)?
I had a similar requirement and what i have done in order to allow a 'label' on a report to be formatted in certain circumstances is:
1. My report is basically based on a query that is based on a single table, so if your report is already based on a query all good and well and proceed to step 3 below.
2. If not then create a query based on the relevant table and just add all the necessary fields from the base table.
3. When i created the query i added an expression by typing in a blank text field of the query want it is i wished to be displayed as a 'label, for example "D.O.B" (include the " "), when you press enter, Access will automatically place Expr1: in front of it.
4. Make sure that the show box is ticked below where you have just created this new entry. Save the query with a suitable name if needed.
5. Open up the report in design view.
6. If your report was already based on a query go to Step 7. If not you will need to change the Reports Record Source through the Reports properties. Providing you have made no other changes to the fields - only added the new expression, you should be able to attach the report to the new query by clicking in the 'Record Source' property and selecting the new Query. This will now update the Reports fields to the query and also make the new expression Expr# (where # is a number, if the only such entry it should be Expr1) available for you. Goto Step 8.
7. If your report was already based on a query and you have added the extra expression (Expr#) to it, you should see it at the bottom of the Reports Field List.
8. Drag and drop this new expression roughly where you want it. Click on the label of this new expression and press Delete, this should leave you with the 'label' Text Box.
9. Set the size, Font etc as required.
10. Right click on this 'label' now should give you the 'Conditional Formatting' option and from here you should be able to set your required formatting such 'Expression Is' and in the box IsNull([YourFieldNameHere]) and set the formatting required if this expression is true i.e. Red and Bold.
11. Repeat as required for each 'label' required to be conditionally formatted.
Because of some complicated Reference Numbers used within my database and the requirement to automatically increment them, I used this process to create a 'label to represent a particular part of the Reference Number i.e. TF-#### with the label providing the TF - section. This allowed me to 'Grey Out' all the fields when records set to superseded in the database are displayed in the report.
It may not be the most efficient method but it works. If you get stuck drop me a line.
Good Luck
Regards
Alan