How to use macros in tstats and calling different macros based on the value of the parameter

[splunkrocks2014]

Hi. I wanted to use a macro to call a different macro based on the parameter and the definition of the sub-macro is from the "tstats" command. For example,

[parentMacro(1)]
args=source
definition=CASE($source$="xyz", `childMacro_xyz`, $source$="abc", `childMacro_abc`)

[childMacro_xyz]
definition= tstats count WHERE index=blah where source="xyz" 

[childMacro_abc]
definition= tstats count WHERE index=blah where source="abc"

I got "Search Factory: Unknown search command 'case'" while using the following

| makeresults 
| eval source="xyz"
|`parentMacro(source)`

Any clues? Thanks.

[gjanders]

 | search`parentMacro(source)`

?
Or include the search command in the macro, although that might only fix the first issue I can see there...