Hello Aneez,
The error means that TestComplete could not find the control mentioned in the "Missing Object" section of the error text. Now you should troubleshoot this situation, and find out what changed in your application, and why your Name Mapping scheme does not match the actual application's state. You need to find out why that GridRow1 object was not found based on the existing mapping criteria (changed properties? changed hierarchy position?).
The best place to start is the
Handling the 'Object Does Not Exist' Error help topic - read it carefully, and use the suggestions given there to find the cause of the problem, and fix it.
I hope this helps!