Insert into Sybase: The token datastream length was not correct. This is an internal protocol error.

Insert into Sybase: The token datastream length was not correct. This is an internal protocol error.

I'm trying to insert data into a Sybase table, with Python, (with one column) through a procedure and I'm getting this error message.
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"The token datastream length was not correct. This is an internal protocol error."

Below is the code I'm using:
my_cursor = my_connection.cursor()
my_cursor.execute("EXECUTE TesteUbdxxxI('s')")
my_cursor.close()

Ps.: TesteUbdxxxI is the name of procedure

Does anyone have any idea what I'm doing wrong?