[R] big data file geting truncated

[Dibakar Ray]

I am very new to R. I was trying to load some publicly available Expression
data in to R.
I used the following commands
 mydata<-read.table("dataALLAMLtrain.txt", header=TRUE, sep
="\t",row.names=NULL)
It reads data without any error
Now if I use
edit(mydata)
It shows only 3916 entries, whereas the actual file contains 7129 entries)
My data is something like
Gene Description	Gene Accession
Number	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	34	35	36	37	38	28	29	30	31	32	33
AFFX-BioB-5_at (endogenous
control)	AFFX-BioB-5_at	-214	-139	-76	-135	-106	-138	-72	-413	5	-88	-165	-67	-92	-113	-107	-117	-476	-81	-44	17	-144	-247	-74	-120	-81	-112	-273	-20	7	-213	-25	-72	-4	15	-318	-32	-124	-135
So it seems R is truncating the data. How  can I load the complete file?
Thanks in advance
Dibakar