lalitswain

Login to https://dashboard.sandbox.checkout.com/

Tick the box against the processing channels id

1. Developers> Key
2. Edit the keys
3. tick the processing channels id against SK and PK

can you please send me your account name ? I can check.

Thanks
Lalit

also make sure you are using the correct set of keys (SB vs Prod)

Please let me know which version of the plugin you are using.