opendir() - Is there a filename cap ?

[Enrique Arredondo]

Why doesn't opendir detect this files :

E-Mitsu183-15-A22-1_0000.gif
E-Mitsu183-15-A22-1_0001.gif
tnailE-Mitsu183-15-A22-1_0000.gif
tnailE-Mitsu183-15-A22-1_0001.gif

I have hundres of files and some are not detected and some are detected , 
Is there a lenght cap ?

Thanks