Go4Expert - Merge-sort issue!

yo yo sup?
so I get this Merge-Sort to be implemented in c,look:

**Please notes this:1-The arrays are not sorted and still I got to merge them.

2-Running time must be of order O(n*log(n))
3-The following code works but I get Runtime Error,so mainly I need your help to find out where the Runtime Error occurs!
4-the two arrays of the same size

Code:

Code:

int merge_sort(int arr1[], int n)

{

int len;

int*temp_array,*base;temp_array=(int*)malloc(sizeof(int)*n);

if(temp_array==NULL){

    printf("Dynamic Allocation Error in merge_sort");

    return FAILURE;

    }

    for(len=1;len<n;len*=2){

        for(base=arr1;base<arr1+n;base+=2*len){

              merge(base,len,base+len,len,temp_array);

              memcpy(base,temp_array,1*len*sizeof(int));

            }

        }

    free(temp_array);

    return SUCCESS;

}

void merge(int a[],int na,int b[],int nb,int c[])

{

 int ia,ib,ic;

 for(ia=ib=ic=0;(ia<na) && (ib<nb);ic++){

    if(a[ia]<b[ib]){

        c[ic]=a[ia];

        ia++;

        }

        else{

            c[ic]=b[ib];

            ib++;

            }

    }

    for(;ia<na;ia++,ic++)c[ic]=a[ia];

    for(;ib<nb;ib++,ic++)c[ic]=b[ib];

}

as u see i implemented merge too,

My problem is that this code works for arrays of length of (in the fir 'for' loop)power to 2,

what u think?

Thanks!