Error using splitapply(Regress)

Hello, I have a given set of values that I was able to divide as groups from a table named 'Change1', however I get the following error message when trying to use the splitapply function:

Error using splitapply (line 61)
Group numbers must be a vector of positive integers, and cannot be a sparse vector.

Error in Untitled (line 8)
Regress = splitapply(func,X,Q);

I named the collumn containing the number that decides of the grouping as 'Numero', the column containing the ones to use for calculating the regressions intercepts as 'Ones'

The code is as follows:

Change1.Groups = findgroups(Change1.Numero);
X = [Change1.Groups Change1.Ones Change1.ReturnsMarket];
Q = Change1.ReturnsCleaned;

func = @(Q)regress(Q,X);

Regress = splitapply(func,X,Q);

[Sindar]

Why are you not using:

Regress = splitapply(func,X,Change1.Groups);