Klas,
What is being returned from TableUpdate()? If it is .F. then the update failed.
Also, if you are using VFP 5.0 or later I would suggest changing tp the newer syntax for tableupdate.
TableUpdate([0,1,2],[T,F],[AliasName], [ArrayName])
The numbers give you better control over what happens. 0 - current row is updated only, 1 - all rows are updated and if any fails the tableupdate fails, 2 - all rows are updated and the array referred to in ArrayName is updated with teh record numbers of any rows that failed to update.