Error on HP50G ODE numeric solver ?!!!


Today with my HP50G ROM 2.15 I try the basic example in chapter 16 from the user guide book...

y'' + 1.962*y' + 18.75*y =0
y'(x=0)=6 and y(x=0)=0

| 0 1 |
|-18.75 -1.962| matrix is store in A

I place 'A*Y' in the "f" field
Indep:X Init:0 Final:2
Soln:Y Init:[0 6]
and the solve command give me:"Non algebraic in expression"

I can't place A*Y (without quotes) in f field as the user guide show... error "Invalid syntax"

I try this way :

'D(Y)' in the f field

D contain the program <<->Y << A Y * >> >> But the same error occur...

When i come back to the VAR menu the var Y=[0 6] X=0 and EQ are there with good initial values...

I try these:

If I place on the edit line 'A*Y' then ENTER the stack show A*Y if I try EVAL the i have the same error "Non algebraic expression" is there something wrong ?

If I place on the stack the vector [0 6] the press D program the result is OK... [6 -11.772] but 'D(Y)' ENTER EVAL give the "Non algebraic expression" error.

Before sending these message I search in old contribution and i found in 2003 year a same problem but with a HP49G... Jean-Yves Avenard wrote "This was a bug fixed in ROM 1.20 of the 49G+ .. "

I did something wrong ?

Thank's for your help.