Way to assign missing coordinate system on annotation?

[DaveMartin1]

I'm trying to Upgrade Dataset on an annotation feature class.  When I run the tool, I get the following error:  Error 002146: Upgrading annotation with an unknown coordinate system is not supported.  It seems as though the coordinate system was not assigned when the Anno FC was created.  Is there to assign the coordinate s system now?

[wizgis]

@DaveMartin1 

I guess Define Projection tool can be used to assign projection to the annotation feature class

[DaveMartin1]

@wizgis... Unfortunately this did not work.  The initial warning when I run the Upgrade Dataset, says "Upgrading annotation with an unknown coordinate system is not supported".  

When I run the Define Projection tool, I drag a feature class with a known coordinate system into the Coordinate System box, I get the following warning "Cannot get exclusive schema lock. Either being edited or in use by another application or service".

Any thoughts?