Error: incompatible types for 'shared(SysTime)' and 'shared(SysTime)'

[Luke Picardo via Digitalmars-d-learn]

if (curTime - lastMsgTime).total!"seconds") ...
Both are shared Durations.

also when I try to do

lastMsgTime = curTime;

Gives me

Error: non-shared method std.datetime.SysTime.opAssign is not 
callable using a shared object.