How can evaluate expression in Immediate window about concordextensibilitysamples HOT 2 OPEN

i had try many EvaluateExpression pattern code,now this work:
var rootExpr = (DkmRootVisualizedExpression)visualizedExpression;
var ParentInspectionContext = visualizedExpression.InspectionContext;
using (var expression = DkmLanguageExpression.Create(ParentInspectionContext.Language, DkmEvaluationFlags.DesignTime, $"sizeof({rootExpr.FullName})", null))
{
var worklist = DkmWorkList.Create(null);
ParentInspectionContext.EvaluateExpression(worklist, expression, rootExpr.StackFrame, asyncResult =>
{
if (asyncResult.ResultObject is DkmSuccessEvaluationResult succResult)
{
Debug.Fail(succResult.Value);
}
if (asyncResult.ResultObject is DkmFailedEvaluationResult failResult)
{
Debug.Fail(failResult.ErrorMessage);
}
});
worklist.Execute();
}

from concordextensibilitysamples.

but when i capture some var in callback,the evaluate failed,Examplae Code:
var size = 0;
var worklist = DkmWorkList.Create(null);
ParentInspectionContext.EvaluateExpression(worklist, expression, rootExpr.StackFrame, asyncResult =>
{
if (asyncResult.ResultObject is DkmSuccessEvaluationResult succResult)
{
if(int.TryParse(succResult.Value,out size);
}
if (asyncResult.ResultObject is DkmFailedEvaluationResult failResult)
{
Debug.Fail(failResult.ErrorMessage); //go there
}
});
the log output :
RETURN ERROR: IDkmMemoryOperation.ReadMemory (hr = 0x92330010, ThreadId=21736, TickCount=703159171)
RETURN ERROR: IDkmMemoryOperation.ReadMemory (hr = 0x92330010, ThreadId=5032, TickCount=703159171)
RETURN ERROR: IDkmCustomVisualizer.EvaluateVisualizedExpression (hr = 0x92330010, ThreadId=5032, TickCount=703159187)

from concordextensibilitysamples.