I don't absolutly sure about this respond.

AL16UTF16 support ASCII coding in second byte of 2-bytes word.
ASCII --> second byte 0000-007F
WE8ISO8859P1 use first byte as ASCII code
WE8ISO8859P1 --> first byte 00-7F

Probably AL16UTF16 and WE8ISO8859P1 incompatible.

U may use UTF8, because:
ASCII(UTF8) --> first byte 00-7F
WE8ISO8859P1 --> first byte 00-7F