> 'WithinDesign', Meas
This doesn't look right with Meas only having one possibility. Try removing that.
> all data are from one mouse. Am i even using the right test?
I don't think so. The analysis you are doing is for situations where you have many randomly selected subject/mice and multiple measures on each one. If you have only one mouse, then the trials are the only source of random variation in the data set so the trials are the "subjects" and it is essentially a between-Ss design (i.e., each trial is only tested in one condition). But the results of the ANOVA will only tell you about systematic effects for this one mouse, and you will have no statistical basis for generalizing to other mice. For that, you would need multiple mice.