skipped due to megabytes problem

So sorry to be a bother.
I am analyzing a big autosomal dominant pedigree diagnosed with Fahr's disease using the GREAT Merlin (parametric linkage analysis).
I filtered and extracted markers from chr8 (644 SNPs in total) and prepared input files that Merlin requires.
But it crashed with "megabytes" problem and Merlin skipped analyzing. I tried to add --megabytes option with 600000 but still failed.
Would you please be so kind to help me with this problem? Thank you!

Sincerely,
Yi-Heng Zeng
Fujian Medical University, China

Here is my command:

merlin -d cxj-chr8-7.dat -p cxj-chr8-7.ped -m cxj-chr8-7.map --model cxj-chr8-7.model --grid 1 --markerNames --pdf --tabulate --bits 60 --megabytes 600000

Here is the error log:

Estimating allele frequencies... [using all genotypes]
...................................................
Done estimating frequencies for 654 markers

Analysis models will be retrieved from file [cxj-chr8-7.model]...
Input: VERY_RARE_DISEASE 0.0001  0.0001,1.0000,1.000   Dominant_Model
Validated: Loaded model 'Dominant_Model'
Table processed. 1 models recognized

Family:     1 - Founders: 13 - Descendants: 32 - Bits: 51
**SKIPPED: At least -24139 megabytes needed**