I test your sence just now, and IK tools worked well.The errors your get may be due to the null variables,u can restart the IK tools to deal with the problems.(restart IK tools can initialize all variables)
As regards your suggestion,i correct two potential problems.
1:display name of root
2:in the past,when the animation range in current 3dsmax's setting were out of the range in current IK tools' setting,u would get a wrong result.Now IK tools can edit 3dsmax's setting of animation range automatically.
as before,here is the right sence and improved IK tools