circular reference error in user defined function

[caseyw8]

Hello,

I'm new to Excel and trying to figure out how to define my own function. I'm getting a circular reference error when I try to run my function, but I can't see any problem with the code. Any help would be very much appreciated! Thanks! Here is the code:
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Option Explicit

Function MELT(S As Double, albedo As Double, beta As Double, D As Double)
Dim A As Double
Dim B As Double
Dim T As Double
Dim sigma As Double
Dim L As Double
Dim dt As Double

sigma = 5.67 * (10 ^ -8) 'stefan boltzmann constant (W m^-2 K^-4)
T = 273.15 'surface temperature of ice during melt season (K)
A = -3 * sigma * T ^ 4 'blackbody radiation constant (W m^-2)
B = 4 * sigma * T ^ 3 'blackbody radiation constant (W m^-2 K^-1)
L = 3 * 10 ^ 8 'Latent heat of fusion (J m^-3)
dt = 60 * 60 * 24 * 31 * 3 'length of summer in seconds
MELT = dt * (S * (1 - albedo) + (A + B * T) * (beta - 1) + D / 2) / L 'total melt = melt rate * length of summer in seconds
End Function
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[Norie]

Can you post an example of how you are using the function in a cell?

PS Can you add code tags when posting code?

[caseyw8]

Thanks for the quick reply! I'm simply going to a cell and typing something like this: =MELT(300,.6,.5,100)
Sorry if there is a very simple mistake I'm making.

[Norie]

When I try the formula posted in a cell I get a #VALUE! error, caused by this line which generates an overflow.

dt = 60 * 60 * 24 * 31 * 3 'length of summer in seconds

However I don't get a circular reference/warning.

Are there any other formulas on the spreadsheet?