The error is occurred because you do not enter correct genetic code.
See 7.Annotation -- Organism name.
To specify genetic code, enter digit in the input field.
The value will be automatically applied for /transl_table qualifier for CDS feature.

For your information, in case of a previously reported organism, the genetic code is automatically specified, by describing Scientific name (/organism qualifier) and /organelle qualifier. If your sequence is derived from an organelle other than nuclei, you have to specify /organelle qualifier to set the genetic code for mitochondrion, chloroplast or some, appropriately.

References
7.Annotation
7.Annotation – Organism name
The Genetic Codes
About /transl_table qualifier