仍然是李军车练习,又出错,请高手指点.提示如下...

做李军车的练习,一错解决有出一错,
快崩溃了,高手指点一下.......
出错信息提示如下:

ERROR: ---------------------------------------------------------------------
ERROR: "object" is not a known constant, function or variable
ERROR: (<<object>>.parent.name != "ROOT DATABASE OBJECT")
ERROR: The command was not executed.
ERROR: +1>> if con=(object.parent.name != "ROOT DATABASE OBJECT")
ERROR: ---------------------------------------------------------------------

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WARNING: ADAMS has issued 4 warning(s) for the normal force moment arm
for the rolling resistance moment. ADAMS will no longer
issue these warnings.
ERROR: Problem evaluating VARIABLE mycar_1.radius.
Tried to divide by zero while evaluating its function expression.
Divisor was 0.0. Examine the function expression to determine why a
divide-by-zero was attempted.
ERROR: Abnormal termination encountered in Solver.