Select error

Hello all,

How can a simple statement like this one:

SELECT SINGLE * FROM tbl_smt INTO ls_smt

WHERE field = p_field.

<b>always</b> return sy-subrc = 4 ?

p_field is declared <i>like tbl_smt-field</i>

and is in fact a CHAR of length 30.

tbl_smt contains a few lines with data.

p_field is not a key field.