Subscripted assignment dimension mismatch

I know what the error mean. But I cant see why iam getting it.

for h=1:2
%%DFT
X(h,:)=fft(u(h,:));    get the error in this line
.
.
.
end

>> size(u(h,:))

ans =

             1       60000

>> size(u)

ans =

             2       60000

[Mark]

Does X exist already when you reach that line? Is it at least 2 x 60000 in size?

[Andre]

Thats it. The X was stated earlier in the script.