You cannot directly call xmlget in a Run Script action. You can, however, use it with the Watch.ExpandString command. Example:
Watch.SetVariable "global.XMLDocTypeTxt", Watch.ExpandString("xmlget('/quartile',Value,KeepCase,NoTrim)
This should properly set the variable to the value you are looking for, assuming your xml path is correct.
Hope that helps!
RaphaŽl Lalonde Lefebvre