I use Stata, rather than SPSS. In Stata, your command for agef would not work because the maximum value would be calculated just for non-missing values. If a child has not had the measles immunization, for example, then the date of that immunization, and the child's age at that immunization, would be missing and therefore would be ignored. The command will give the maximum age at receiving the immunizations THAT HAVE BEEN RECEIVED, not necessarily the age at receiving ALL immunizations. I suspect that the "max" command in SPSS works the same way (sorry if I'm wrong about that!).
There are two ways around this. One would be the following. If the child has not (or not yet) received an immunization, set the age to a high numeric value such as 1000. Then the children who have not yet received all immunizations would have agef=1000. Alternatively, after the line to calculate agef, add another line to replace it with a missing value if any of the components (bage, etc.) is missing. In Stata, the lines would be as follows:

egen agef=rowmax(bage p1age p2age p3age d1age d2age d3age mage)
replace agef=. if bage==. | p1age==. | p2age==. | p3age==. | d1age==. | d2age==. | d3age==. | mage==. 

As a minor comment, your labels for the CMC variables are misleading. For example, "Var Lab CMCB "Century Month Code of age at BCG." should be "Var Lab CMCB "Century Month Code for month of BCG." These variables are a recoding of dates, not of ages.