Randal,
in addition to all, if you use version 8 or above there are a veery beautiful function and method named NewObject() (I realy love them)
You said that his class is defined in Main.Prg so in init event of the form:

thisform.NewObject([oMsm],[MSM],[Main.Prg])
thisform.oMsm.lds = [C:\....\comp.dbc]
thisform.oMsm.synchro()

>hi,
>I need help in this code.
> In my main.prg i have the follwing piece of code
>
>DEFINE CLASS MSM as Session OLEPUBLIC
>lds=""
>rds=""
>
>
>function synchro
>....some code
>endfunc
>..some more functions
>enddefine
>
>I have a form which has got a command button. The code behind for this button is:
>
>thisform.lds= "C:\....\comp.dbc"
>thisform.synchro()
>
>
>when i run the form i get the foll. error
>
>Property LDS not found
>Property SYNCHRO not found
>
>Why Am i getting this error. Im new to Object oriented VFP.