From the subject of your post, it looks like you need to enter a suitable model name for the diode. Actually it is a little hard to provide more help because there is a lack of information. E.g.
- What kind of pdk are you using? (e.g. I am using 90nm pdk from ABC foundry)
- How did you encounter the error? (e.g. I encountered the error when using spectre 12.1.1 in ADE-L 6.16)
- What is the exact help that you need? (e.g. I cannot enter a width value because the field has been disabled in the properties form, etc).
Would you please provide more details on the problem so that we can help to decide if you should seek help from Cadence or the foundry?