Hi Venu,
Thanks for reply.
First
I followed your steps. I entered Technical Service name ( already exist ) and clicked on change.
But Service Information and Model Information blocks are already filled with their respective DPC_EXT and MPC_EXT .
And Model Information Block is non editable .
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Second
After That i clicked on Create Model and entered model class like this.
And then go to /iwfnd/maint_service, showing same error.