DBIF_RSQL_INVALID_RSQL between different type transfer

{code}

select single fieldA into l_val from table ZZZ where key1 = l_key.

{code}

fieldA type char8,

l_val type int4.

the key1 and l_key has the same type.

In my selection, the fieldA will be '301'.

Is the type difference which caused the dump?

It's OK in DEV and failed in PRD.