Would it be quicker to just do the following:

ALINES(laFinal, SUBSTR(lcString, 2), "A")

or for vfp 6

ALINES(laFinal, STRTRAN(SUBSTR(lcString, 2), "A", CHR(13)), "A")

But the reason there was a problem with your other code is you cant return a pointer to a variable ( especially if it is going out of range after a return). you would need to pass a pointer to the array in one of the parameters like this:

LOCAL ARRAY laTest[3]

CallFunc(@laTest)

FUNCTION CallFunc(laExtArray)
EXTERNAL ARRAY laExtArray
?ALEN(laExtArray)
ENDFUNC