>Below is part of the function
>
>LOCKFIL(haud,'haud')
>PURGE('haud.cdx','') <----- this part will give error
>INDEX ON .... TAG test1 of haud
>INDEX on ....
>
>LOCKFIL(daud,'daud')
>PURGE('daud.cdx','')
>INDEX on.. ...
>
>FUNC LOCKFILE(pFileName,pAlias)
> USE (pFileName) IN 0 ALIAS (pAlias) EXCLUSIVE
>ENDFUNC
>
>FUNC PURGE(pCdxFile,pAlias)
* I think it would go better with
SELECT (pAlias) && here.
> DELETE TAG ALL OF (pCdxFile)
>ENDFUNC

but I'm not sure if that's your whole problem.

You definitely have to have the work-area selected for the table you want to index by the time you execute INDEX ON...

HTH