Simple Data & Time VBA Error

[Legacy 185509]

Hi
in cell C1 I have data & Time like this, 7/12/2011 15:00:00 PM (look at pic below for format type)
and I made a macro to add month & date
like this
if time is less than 12, I am able to add 1 & 30 by using this macro below, but if time is like 15:00:00 I get debug error please help
thank you

Sub mpluz()
Sheets("Sheet1").Select
Range("C1") = Range("C1") + 30
End Sub

Sub pluz()
Sheets("Sheet1").Select
Range("C1") = Range("C1") + 1
End Sub

like this

 

[Derek Brown]

Try:

Range("C1").Value = Range("C1").Value + 30

Does that make a difference?

 

[Legacy 185509]

nope it still doesn't work
if the cell date and time is set to
6/10/2011 12:59:59 PM
if it is set to
6/10/2011 13:00:00 PM it doesn't work