To edit Desired Properties ECExpression in schema through Bentley Class Editor..
When editing ECExpression value in required class property, software sometimes prompts warning about wrong value and rejects saving.
In this example a ECEXpression of NAME property was edited, then after editing, other property selected and then all changes saved. If any other field, inside the same property, will be selected, then this warning might start to popup.
If you already are getting this warning and you can't do any changes, then click cancel. It will return for you earlier ECExpresion value.
After each ECExpression editing, any other property should be selected first and then changes will be approved and you will be able to save them.
If above problem still persist, then please create a Service Request and contact Bentley Product Advantage group along with the list of all relevant details to get in depth analysis and for possible solution or workarounds.
http://communities.bentley.com/products/plant/design___engineering/w/plant_design_and_engineering__wiki/31216.fundamentals-basics-of-class-editor-schemas
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