Question: Maple's GUI is making crucial mistakes

I type in:

--------------------------------------------------------------------

RET := λbar*R :

RET[Sigma] := cos(RET)+RET*sin(RET):

C6[Sigma]+(C3[Sigma]*RET[Sigma])^2/(4*De);

--------------------------------------------------------------------

It displays fine on my GUI, but when I copy and paste it into a text editor I get:

RET := λbar*R :

RET[Sigma] := cos(RET)+RET*sin(RET):

C6[Sigma]+(C*3[Sigma]*RE*T[Sigma])^2/(4*De);

--------------------------------------------------------------------

Which is the same except in the last line where it says "RE*T[..."  that is INCREDIBLY annoying and I don't know how to fix it.  In fact maple is TREATING that expression in the last line as R*E*T , which I found out later when I saw the expression R^2 E^2 T^2 printed out.  It is strange because it treats RET as ONE variable in the first two lines, but in the third line in splits it into three variables: R, E and T. Also, 'C3' comes out at 'C*3' .. I'm not sure if Maple is treating this is C times 3.

--------------------------------------------------------------------

Ok, so I redefined everything:

T := λbar*R;
T[Sigma] := cos(T)+T*sin(T);
C6[Sigma]+(C*3[Sigma]*T[Sigma])^2/(4*De);

--------------------------------------------------------------------

which gives me:

Error, `[` unexpected

I find this message quite uninformitive. Does anybody know what it means ??

If anyone knows how to fix either of the two above problems, I'd be very thankful.