Sorting a hash

Hello,

I am trying to sort a hash of hashes.

my code looks like this

 foreach $cnt (sort keys %{ $relations{ $uid }{ "instances" } }){
             print OUT "$cnt 1, ";
 }

This prints out the correct numbers (the keys of the instances hash.
However the sorting is a bit weird.  The keys are all integers yet
when sorting the keys aren't put in number order. instead the first
digit is seen as the qualifier.

Here is an example output:

 100 1, 120 1, 121 1, 122 1, 123 1, 124 1, 125 1, 126 1, 127 1, 132 1,
133 1, 134 1, 135 1, 136 1, 137 1, 138 1, 139 1, 221 1, 222 1, 223 1,
224 1, 225 1, 226 1, 227 1, 228 1, 235 1, 236 1, 237 1, 238 1, 239 1,
240 1, 241 1, 242 1, 323 1, 324 1, 325 1, 326 1, 327 1, 328 1, 329 1,
330 1, 50 1, 51 1, 52 1, 53 1, 54 1, 55 1, 56 1, 57 1, 93 1, 94 1, 95
1, 96 1, 97 1, 98 1, 99 1,

As you can see it is not in normal order.

Does anyone know why this is happening and how I can fix it?

Thanks