delisting return CRSP

[Nieves]

Hi SAS experts, 

How to implement the following requirement for adjusting delisting return ? 

if a stock disappears from CRSP,its delisting return (dlret) is used in the month after its last month of reported returns (ret)

For example: 

data.have is as follows:

permno	date	prc	ret	dlprc	dlret
10000	1-Jun-87	-0.21875	0
10000	2-Jun-87	-0.21875	0
10000	3-Jun-87	-0.21875	0
10000	4-Jun-87	-0.21875	0
10000	5-Jun-87	-0.21875	0
10000	8-Jun-87	-0.21875	0
10000	9-Jun-87	-0.21875	0
10000	10-Jun-87	-0.21875	0
10000	11-Jun-87	-0.21875	0	-0.21875	0

data want:

permno	date	prc	ret	dlprc	dlret
10000	1-Jun-87	-0.21875	0
10000	2-Jun-87	-0.21875	0
10000	3-Jun-87	-0.21875	0
10000	4-Jun-87	-0.21875	0
10000	5-Jun-87	-0.21875	0
10000	8-Jun-87	-0.21875	0
10000	9-Jun-87	-0.21875	0
10000	10-Jun-87	-0.21875	0
10000	11-Jun-87	-0.21875	0	-0.21875	0

10000

12-Jun-87

-0.21875

0

Is it correct to use the following code to implement:

if not missing(dlret)  and last.permno then ret = dlret;

[Quentin]

Please add some sample data your to question, and show the output data you want to create from that sample data.  That would help people who are unfamiliar with financial analysis.  Also please show what code you have tried, and describe how it is failing.